At your age you will probably pack on tons of muscle when you start working out. Your hormones are probably starting to spike right now to the point that you'll gain a lot of muscle, quick. Not to mention newbie gains that will come with just starting to lift.
Between the ages of 15 and 16 I put on a good 30 lbs of lean mass, didn't really gain fat at all. Wish I could do the same now and eat the same way I did then! Almost seemed effortless (I'm only 22 now but much closer to max potential). Granted, not everyone is the same but I wouldn't obsess over your hormones at this point in life.
Eat, lift, sleep, grow.
If you start to gain too much fat cut back a little bit but I doubt you'll run into that to be honest.