Hey, I'm the definition of a hard-gainer. I weight about 150-155 and am 6'0". I have been stuck on my flat bench for about 10 months, maxed at about 170lbs. I can put up 225lbs on decline and about 150 on incline bench. Why is my flat bench lagging behind so much? I also have a gap in between my pecs and I am having trouble filling that in. I used to do 3 sets of flat bench, but I upped it to 5. Am I on the right track to build it up?

I also take 2 large protein shakes everyday, 1 before/after I lift, and 1 before bed.