Wow! I remember weighing 145lbs. Than 160lbs, than 180lbs, than suddenly 240. As you get older your muscle maturity will kick in and you will be able to gain weight. You do not have to gain weight to gain muscle. I won my first NPC bodybuilding competition at 143lbs. It is very common for younger athletes to maintain lower weight levels while putting on pure muscle. For example, you may lose 5 lbs of scale weight, but gain 10lbs of pure muscle. When this hapens on smaller athletes, it looks like they put on 20lbs of weight and their strength will keep going up. This is how you know you are putting on muscle if you are not gaining scale weight. Being a hard gainer sucks. Than over the years you maturity will kick in and beleive me, you will have no problem gaining weight.
As a running back, and if you are not going to be tested for a while, I would stay away from test cypionate, enanthate, dbol, anadrol. Although these drugs are great for putting on weight, once you get off of them, their is usually a fatty rebound effect. As a running back, you cannot take a chance for this to happen. Furthermore, they watch for too fast of gains by young atheltes, and these days will actually hold quick achievements against you. I know scouts, and they will wait a while if an athlete rises quickly through the ranks. Your young, so they watch. Over time it is easy to see who is taking them. Your best bet is to start off with winstrol and work out as hard as you can. Winstrol will make you run fast, look good, and get attention. Thats all you want now. Than once you have gotten noticed, and you will, they will see that your gains were not "crazy", and they will actually respect you more thinking that you are deffinately natural. Your name will slowly get around. You dont want yourself becoming the guy who put on 30lbs in 3 months and is gaining and losing weight like a yoyo. They will hold it aginst you. Take it slow. You have time. Once they notice you take a little sustanon250 in the off season with some Winstrol (winny) again. Than when you go back you will have the natural gains they will brag about. Can't stress it enough. Take it slow.
Once you are playing for a d1 team. During the on seasone the best drug to take is GH and test suspension.
By the way, the GCMS test for stanozolol is a lot better these days. 6months-8months is possible to detect. Just ask Rafiel Palmero of the Baltimore Orioles he was 7months clean off of Winstrol (winny) and popped. Ways of beating it though.