Well one major problem just from reading your post is that you are starting out with decline.... the least beneficial of all the chest angles. I agree with Most everything roid noid said. i suggest 3 incline pressing movements 3 flat pressing movesments 2 decline strict -stretch movements, 2-3 sets incline flies 2-3 sets flat flies 2 sets decline optional. Reomove tricep day from chest day. if both muscles are used in same exercises...... one muscle is going to get crappier w/o. no avoiding it. warmup. set of 12. set of 8-10 set 0f 8-10. this is how your sets should run. only warm up at start of muscle group.... not every exercise.

Brother, the secret to a strong chest is a strong back...

I actually needed to bring the width of my hands in on the bar. then i make sure on the incline bench i bring it to damn near my neck and get a real good stretch. if you are looking to body build, you might want to lower the weight and focus on body building, not strength.
try also to lower the time between sets.
another thing that helped me was push ups too. also those you van do damn near every day so...

Mate have a read of my post slow down and grow. The reason it works is you feel the muscle working that you are targeting. Look into Dorian Yates Blood and Guts training mate. It is bloody hard core but it works and it works very well. If it is good enough for him to win 6 Mr Olympias then it's good enough for me.

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Chest is one of my favorite muscle to hit, so a few pointers in getting a well developed strong chest. First of all work chest and triceps together, this way triceps are not fatigued from another day, when you work them together they rest together, very important for heavy bench. Also for you, your shoulders are well developed so theres no reason why you should do shoulders before chest, believe it or not a hard shoulder press day will effect bench 2 days later. So I would recommend
chest triceps
shoulders/traps
back/bi
legs
rest
repeat
or something similar to this, for maximum chest strength dont work it more than once every 5 days. Ok for development, alot of people dont realize that there is an upper, middle, lower, inner and outer, and to really make it pop you got to hit most of it. 45 minutes on chest is the minimum time allocated to do what needs to be done, everytime I hit chest ill do flat bench, incline bench, flat bench dumbells, incline bench dumbells, weighted dips or decline bench, standing cable crossovers, and cable flies, also I like to do these cheesy bouncing pushups, go all the way to the floor then come up about 6 inches and back down real fast, do them in sets of 50 real fast, it will fill the chest up full of blood, then ill stand up and squeeze them real hard for 20 seconds... on cycle I will add to that, everything consists of a minimum of 4 sets, 10,8,8,6...Now for the strength, have you ever used a heavy chain tied to the end of the bar? very effective for building strength, next suggestion is forced reps, simple stuff just get a spot and make him force you to do a couple extra reps. But my favorite is negative failure, these hurt like hell and aint for pussies, you get a good spotter that can lift the weight off of you, bang out the first 8 reps or so, then struggle for 2 or 3 to where you cant lift the weight no more, then without racking it you take the weight down very controlled till the bar touches your chest and then the spotter snatches it back up real fast so you get no break and you then try to control the weight back down, by the third one you shouldnt be able to control the weight down any more, the spotter snatches it up and racks it and you go cry for a minute. Do three sets like this and you will grow like a fucking weed, you will hurt and hate me for it but its the fastest way I know how to gain strength. By the time you get done with chest there shouldnt be but about 10 to 14 sets left for triceps, they will be pretty fatigued if you do chest right.

try doing dumbbell flys instead of machine. If you do them the right way so as not to make it a pressing movement and get a huge stretch at the bottom keeping a nice arch coming up the chest will grow quite quickly. Looks like you have some gifted shoulders and arms, so they may be working to hard when your benching cause they are dominant, I would suggest taking a wider grip on bench and incline and concentrate real hard at making the chest bare all the load.

Also, dumbell pullovers done right for chest are clutch. . So maybe something like:

Incline Bar/dumbell 3x 12-8
slight decline or flat ( dumbell/bar) 3x 12-8
Dumbell flys 3 x 8
Dumbell pullover 3 x15

Switching up the order of the flat and incline and alternating dumbell to barbells each workout like someone else just said is def. solid advice.
I'de also throw in a heavy day once a month

Bench and Incline 8 sets 20rps, 10, 5, 3, 2, 1, 1, 1 than move on the flys and pullovers.

Chest was very hard one for me years ago and I still can't bench press a whole lot, but my chest is now drastically bigger.

Conquered it yes. You absolutely HAVE to hit all angles regardless of pride. Not everyone has same strength on bench. IMO bench bragging is bs. He benches 250.....so what....i single arm row 250. But it doesn't help at all for personal goals. Without incline bench you're wide shoulders and pokey collar bones. Looks funny right? Or guy at gym with 20in arms and nothing else. Start with a 10-12rep incline for 4sets. At leadt two mins between so you can lift heavy. Then blast you 10-12 x4 decline. Then flat bench. Flat will be lots heavier because upper n lower is exhausted. Next chest day hit lower then upper followed by bench. Shock the system. You'll jump up quickly in both size and strength. Everyone has a lagging bodypart.

Warm shoulders with rotations and first set light reps. Stretch AFTER so ligaments are warm and have oxy but still hold joint tight.