I think there’s a lot of good discussion here, but I also think we’re missing a larger part of the story. Eight cycles and only mentioning the last one is like showing us one chapter of the book. And not the most important chapters.

Looking strictly at the labs, I don’t think this is an HPTA problem at all. Your LH and FSH are elevated and your total T is actually higher than pre-cycle, so your brain and testes are clearly communicating. The issue seems to be that very little of that testosterone is actually available.

The biggest red flags to me are the IGF-1 of 79 and the SHBG of 65. If you truly crashed yourself with an aggressive Retatrutide cut, that could absolutely explain the picture. Severe calorie restriction and rapid weight loss can drive SHBG up, suppress IGF-1, lower leptin and thyroid activity, and completely destroy libido even with a respectable total testosterone.

I’d also be careful assuming finasteride is innocent just because you’ve used it for 15 years. Maybe it was never a problem when your free T was high, but now that your free T is in the basement, the additional reduction in DHT could be enough to push you into ED and zero libido. I’d definitely want to see a DHT level.

Personally, I think lingering NPP is lower on the list. Nine months later, with LH/FSH that high and total T recovered, I have a hard time blaming nandrolone as the primary driver.

Before jumping to Proviron, I’d fix the obvious stuff first. Get out of the deficit, get calories back up, regain some body mass if needed, let IGF-1 recover, and retest SHBG and free T in 6 or 8 weeks. I’d also make sure that free T was measured accurately because direct assays can be way off.

One other thing that deserves attention is the lurasidone. Even if it never caused problems before, changing your entire metabolic state can change how medications affect you, and dopamine blockade itself can contribute to sexual dysfunction. That’s something to review with the prescribing doctor rather than trying to out-supplement it.

My gut says this is much more likely a starvation/high SHBG/low free T situation with finasteride adding fuel to the fire than some mysterious permanent NPP neurosteroid damage.

I think you should tell the whole story, at least a minimum use history of five years before giving us just a chapter.

Nolvadex alone is a dumb PCT if your goal is to reset the motor.

Brother, you've actually diagnosed yourself better than most of the thread your read that this is an SHBG/free-T lock rather than an HPTA failure is correct, and your bloods prove it. But there's a piece in your own medication list that nobody's flagged, and it might be the biggest single factor. Let me order this properly.
First, confirming what you got right:
Your HPTA is genuinely recovered. LH 13.5, FSH 17.7, total T 759 (above your pre-cycle 693) your brain and testes are working fine. This is not HPTA suppression. So the "is this lingering NPP wreckage shutting down my axis" worry is off the table; your axis is firing. Good.
The problem is exactly what you identified: free T 16 (crashed from 93) because SHBG is at 65 and binding it all up. Total T looks great, free T is the floor, and SHBG is the culprit. Your detective work there is correct. You have plenty of testosterone; almost none of it is bioavailable because SHBG is locking it up. That's the whole picture of your symptoms zero libido, ED, feeling asexual because free T is what drives those, not total T.
Now the thing nobody in the thread caught and it might be the headline:
You listed lurasidone 60mg in your daily meds, noting you've run it 15 years with no libido issues. Lurasidone (Latuda) is an antipsychotic, and here's the relevant part: estrogen and thyroid status and metabolic state all affect SHBG, but so does your overall hepatic and metabolic environment and a severe starvation deficit dramatically raises SHBG. That's the mechanism you correctly identified with the reta. But the reason I'm flagging the lurasidone isn't SHBG directly it's that you've changed your entire metabolic and hepatic state with the extreme reta deficit, and that can change how every other drug in your system behaves, including ones you've taken stably for years. A medication that was fine for 15 years at a stable metabolic baseline isn't guaranteed to behave the same when you've crashed your IGF-1, spiked your SHBG, and put yourself in severe starvation. The "I've run it for years with no issues" logic doesn't fully hold when the underlying metabolic terrain has shifted this much.
More importantly: lurasidone is an antipsychotic, and you should not be making changes to it or running aggressive cuts and hormonal experiments around it without the prescribing doctor in the loop. This is the single biggest reason you need a doctor and not a forum. The interactions between a serious cut, hormonal manipulation, finasteride, minoxidil, and an antipsychotic are not something to sort out with proviron from a forum thread. Whoever prescribes the lurasidone needs to be part of this conversation, because that medication matters for your mental health and the rest of what you're doing is happening around it without medical oversight.
The SHBG/IGF-1/starvation mechanism you identified you're right:
Severe caloric deficit raises SHBG substantially. The mechanism is partly the IGF-1 crash (yours tanked to 79, which is genuinely low) IGF-1 normally suppresses SHBG production by the liver, so when you crashed IGF-1 through starvation, you removed the brake on SHBG, and it climbed to 65. So the chain is: reta-driven severe deficit → IGF-1 crashes → SHBG rises → free T gets bound up → libido and erections die. Your read on this is correct and it's the core of the problem.
The good news in that: it's largely reversible. SHBG driven up by starvation/low IGF-1 comes back down when you restore adequate nutrition and your IGF-1 recovers. You're not looking at permanent damage from this mechanism you're looking at a metabolic state that needs correcting. Stop the aggressive deficit, eat at maintenance or a slight surplus, let your IGF-1 recover, and SHBG should fall and free T should rise. That alone may resolve a large part of this.
The finasteride piece Electricladyland asked the right question:
You need to test your DHT level. Finasteride blocks DHT, and DHT is genuinely important for libido and erectile function arguably more than testosterone itself for some men. You've run finasteride 15 years, but again, on top of crashed free T and a starvation state, the DHT suppression that was tolerable when your free T was 93 might be the thing that tips you into total ED when your free T is 16. It's the stacking finasteride-suppressed DHT was survivable with high free T; with crushed free T it may not be. Get a DHT level drawn. If it's on the floor, that's a major contributor, and it's a conversation with your doctor about whether the finasteride is worth it given what's happening (the same DHT suppression that protects your hair is suppressing the androgen signaling that drives your libido).
On the proviron question you asked:
CLAPPER's suggestion of microdosed proviron has real logic proviron binds SHBG, freeing up your bound testosterone, and at 12.5mg it likely won't suppress your recovered LH meaningfully over a short period. So mechanistically it could help your specific problem (it's almost tailor-made for an SHBG-lock situation). BUT two caveats. First, proviron is a DHT derivative, so on top of finasteride it's a weird combination (you're blocking DHT with one drug and adding a DHT-like compound with another), and it'll worsen your hair loss. Second, and more importantly: you just recovered your HPTA after 8 cycles and a difficult PCT. Adding an androgen back in, even a mild one, when you've finally gotten your natural production working, is a real decision not because 12.5mg proviron will necessarily re-suppress you, but because you're in a fragile, recently-recovered state and the smarter play is probably to fix the underlying cause (the starvation/IGF-1/SHBG chain) rather than mask it by chemically unbinding your testosterone. Fix the cause first; if free T is still locked after you've restored nutrition and IGF-1, then the proviron conversation makes sense with a doctor.
On the NPP "neurosteroid wreckage" question:
CLAPPER's right that nandrolone metabolites linger for many months (the 12-18 month figure is in the right range), and 19-nors do have progestogenic/neurosteroid effects that can affect mood and sexual function during and after. But your bloods argue against this being the primary driver your prolactin is 15.8 (normal-ish, not the sky-high prolactin you'd expect if NPP progestogenic activity were wrecking your libido), and your axis has fully recovered. So while there might be some lingering 19-nor contribution, the dominant, explanatory, and fixable factor is the SHBG/free-T lock from the starvation cut. Don't let the exotic "neurosteroid wreckage" explanation distract you from the boring, correct, fixable one: you starved yourself, crashed IGF-1, spiked SHBG, and bound up your free T, on top of finasteride-suppressed DHT.
What I'd actually do, in order:
See a men's health doctor or endocrinologist and loop in whoever prescribes your lurasidone. This is non-negotiable given the antipsychotic in your stack and the complexity. This isn't a forum-fixable situation.
Stop the aggressive deficit immediately. Eat at maintenance or slight surplus. This is the root cause. Restore nutrition, let IGF-1 recover, and SHBG should fall. This alone may resolve much of it over weeks to a couple months.
Get a DHT level drawn to see how much finasteride is contributing. Discuss with the doctor whether the finasteride is worth it given your current situation.
Retest SHBG, free T, and IGF-1 in 6-8 weeks after restoring nutrition to confirm the mechanism you should see SHBG falling and free T rising as IGF-1 recovers. That confirms the diagnosis and tells you if anything else is going on.
Hold off on the proviron until you've fixed the underlying cause and have a doctor involved. If free T is still locked after nutrition is restored, then it's a reasonable conversation supervised.
For the immediate ED while you sort the underlying issue fp50's Trimix suggestion is reasonable as a bridge (it works locally regardless of hormones), and that's a doctor conversation too. It treats the symptom while you fix the cause.
The honest bottom line:
You diagnosed the SHBG/free-T lock correctly, and the mechanism is the reta-driven starvation crashing your IGF-1 and spiking SHBG, compounded by finasteride suppressing DHT. The reassuring part: it's largely reversible by fixing the nutrition, and your HPTA is fully recovered so you're not looking at permanent axis damage. The part that needs emphasis: you have an antipsychotic in your daily stack, you've been running aggressive cuts and hormonal experiments around it without medical oversight, and that specifically is why this needs a doctor not a forum. Fix the starvation, get IGF-1 back, test your DHT, loop in your prescriber, and let the SHBG come down before you reach for more compounds. The boring fix (eat, restore IGF-1, get a doctor) is the right one, not another androgen to mask the lock.

What are you using right now? If anything besides a trt dose of test, stop it. Was your libido good during that last cycle? Or did it disappear after?

You need to clear your system and see a mens health doc. And stop depending on Reta. It does more harm than good, thats a hill ill die on, no matter how people come at me

Have you tested your DHT level to see if finasteride crashed it?

Microdosing proviron could be useful for your scenario. 12.5mg won’t down regulate LH at all if used for a short period. Might worsen hair loss though.

Nanadro metabolites stick around for 12-18 months after cessation, so a full recovery takes a very long time for most people.

Try microdosing proviron for a bit, and see if that improves symptoms. Maybe consider a therapeutic dose of HGH as well.

As a person who has suffered with ED for many years, I would recommend checking out Trimix. It is a game changer for me. It does involve an injection in the base of the penis, but it is less painful than pinning testosterone. This clearly does not solve the deeper issue of what is happening with your hormones and sex drive / erections. I would seek out a hormone doctor and give the doctor the full picture and see if they can help.

For Trimix, if you search for trimix/compounding pharmacies you will have lots of options.

I believe Finasteride has some nasty side effects that people complain about alot realated to libido and ED. Not all get it but reading through reddit there are people that swear to never touch it again cause its ruined their sex lives.

edit: just re-read your comment about running them for years prior.

Why come off, just do trt bro

If you are in a big calorie deficit, it's gonna be real hard for you to have high test. I don't know how it directly affects free T, but I guarantee you if you eat a big meal, you'll get horny fo sho.