Is Playing Cornerback the right position for me?

I'm 15 years old 5'5 and 146 lbs. I think I'm fat because I have a gut that's not very visible. I'm kinda fast and I was a RB/CB but they never put me at either position. they always put me at DE or DT during the final 2-3 plays of the game. So, I'm thinking since I'm most likely not to start in high school at DT or DE(which I like to play) I'm thinking about going to a walgreens and buying a box of Acai berry or Hydroxycut. Most likely Hydroxycut, because I want to get skinny and have the body stature of a CB. Since, I'm a eXremely undersized DT/DE/OT I wanted to play OT and DT but I'm too small like people say. I used to come home from practice everyday with headaches from hittin but I didn't care I was playing at DE because I want to be like Julius Peppers my favorite defensive player. So, I'm willing to do anything to get skinny and be a CB. I just gotta be have the agility and smarts of a CB to be a great one probably. What do you think?