You also said that your diet wasn't too strict or something like that. Nutrition is a vast majority of the equation. Really focus on getting at least 1 gram of protein per pound of bodyweight and 2.5 to 3 grams of carbs per lb of bodyweight spread out over a few meals. You could supplement with Creatine, BCAA's, Whey and Casein, and NO2 and become a monster!
Pay attention to the small things too. Hand placement should be about shoulder width or a little greater depending on your frame and arm length. Make sure you're using your chest and not your recruiting your delts too much (i.e. keep you shoulder blades pinched together for the entire set). Don't arch your back when you press up. Bring the weight to right above your nipple NOT your neck.
If this don't get you somewhere then you might want to consider pec implants LOL
[Ref: http://anabolicminds.com/forum/training-forum/93743-chest-training.html#post1344907 ]