I had the saame problem with you. I woked the chest hard for years and years only doing benches and inclines, but my chest never grew. I am 6ft and have rather long arms and my shoulders always seem to come into play when I do the benches. Probably the worst advice you can get by people telling you to do benches. It may work for some people, but for people like me, and maybe yourself it does nothing. Recently I have started doing decline dumbell presses and it has really worked my chest and for the first time in ten years my chest is looking ok. The reason why I didn't do declines until now is because I listened to people who rubbished the exercise because of the low range of movement. But if you are like me and have long arms you still have to move it a long way. Plus the shoulders don't come into the movement so much. Maybe the declines will not work for you, but you should always give it a try for at least three months. I can't stand hearing people say do benches and inclines. This is so obvious, but it sometimes doesn't work.