my take on this from personal experience is, your not training propperly before 16 yrs of age.. training in your room with shitty barbell sets doesnt count
so now your 16 in a propper gym, if you have coordination and a few helpfull fellows to guide you in right direction you will be close to your natty limit at 18... if you have competitive aspirations you should go on a real cycle ( when i say cycle i mean go on and never realy come off, blast n cruise ) you only have a few years left to make a mark as a jnr so make the most of it
if you dont make a mark, knock it down a peg or two, enjoy your life and dont risk your health chasing the dream