sdgman saidYou do have a good set of shoulders and arms... make sure you are doing correct form with chest.
You see alot of guys over emphasizing the shoulders in chest movements and they really miss out on the benefits.
Make sure whenever you do a chest exercise you pull your scapulae back and down... back and down, make sure you keep them there through the whole movement and you'll see that the work transfers from your shoulders to your chest.
My bench press went up like crazy when I learned that.
^THIS IS VERY GOOD ADVICE!
Form follows function, and thus improves what signals you're sending the body that force it to adapt i.e. grow to compensate for the demand.
A slow responding body part is simply not being asked to adapt to the required need, and thus no need to change in order to function. So you need to look at HOW you're working the chest from a purely mechanical point of view. You have to get your head in the muscle and find the feel.
It's very likely that at first this is going to mean you aren't pushing up the numbers you think you should, and maybe not even the numbers you're pushing up now, but it's very likely that your stabilizers are compensating and your chest is getting off easy.
Also, to pre-empt Chucky, do some basic reading on hypertophy and get a good understanding of the difference between sacroplasmic and myofibrillar hypertophy. It's not as daunting as it sounds, and it will help you format a workout that will give you a better focused approach to your chest training (and your overall training).
I found that watching good form on other lifters/bodybuilders was very helpful. It's all on YouTube, if you go looking. Not the general consumption vids of pros in the gym, but videos where they actually instruct you on the movement. You'll see the difference. And pay attention to how you're aligned in each machine you use, in addition to the mechanics of your free-weight sets.
Tanker has very good advice here, as well. Yes, you need to up your caloric intake, truly. So add some protein and complex carbs to boost your daily intake by at least 500 more calories per day.
Personally, I disagree with training a body-part more than once a week, I think you if you train your chest properly once a week, heavy, strict, and with focus on hitting it from all angles, then you'll see growth, but I'll save that debate for another day.