Quit working out like a bodybuilder. You are doing way too many reps to be properly gaining strength. Go to elitefts.com and find the articles big bad bench, how to bench 600 easy, 9 week basic training program, and train along those lines.
I use the westside program and have put at least 150 lbs on my bench in the last year. And I was benching mid 300's before I ever even started the westside program.
Work your upper back and triceps to death. Move the bar as fast as possible. Pinch your shoulderblades together so you have a firm base and are shortening the stroke, and push in as straight a line as possible.
Read the articles. Do what they say. No gym has ever produced so many world record holders.
B.