You could always tell her your care a lot about her and would like for the relationship to last and feel waiting at least 3 months would strengthen your respect for each other! Lmao!!! I use hcg in my pcts and have discovered that helps my boys bounce back very quickly and my libido responds promptly as well! Have you had bloods drawn? Do you know what your levels are going into and mid pct?

If you think of it like that you won't succeed just be cool calm n collective or you are gnna creep her out n won't even have the chance to fuck. relax my man relax

Keep working out, run, etc

You can always wait another week or so. im sure not too many dudes are trying to put off having sex with her so it could be a huge turn on. what you need to do is STOP STRESSING. Stress alone can make your penis not work properly and also just ruin your performance because you aren't just going with the flow, you are forcing it. Just don't cry when you are fucking her lmao ;-)
regardless man if she really likes you one bad/mediocre encounter won't ruin everything

I have heard it is suppressive but I have heard from many it is not.

Maybe you could run some proviron during PCT also. I'm not sure if it's HPTA suppressive or not.