Dude, no offense, but at 15 I was 6'1, 205. I trained hard as a murf, ate like a government mule, and by the time I was 18 I was 223, a little thick in the middle though. I went to college to play baseball, tore my right rotator cuff and never played again, stopped working out for 2.5 years and waisted down to about 175 before getting back into the gym.

My points are these...you can get the size you want naturally by the time you graduate HS without any gear or prohormones. Second, you can get hurt before you ever play on the college level and then you may regret having a "big at any cost" mentality. I use gear now, but at 15 I know that I wasn't informed nearly enough to use it....and I'm glad I never got into it and risked some pretty nasty side effects from improper usage.