155 lbs at 5'6" and age 13 sounds every bit as much "bulked up" as you need to be. Give it a rest. You will grow at the rate you will grow, and there is very little (and even less safely) that you can do about it. I'd say you are several years (3?) too young to start weight work, and messing with your diet (much less using supplements) is just a poor idea. Focus on your aerobic fitness, core strength, and learning the mechanical skills that are essential to the game. Doing that for the next 3 years or so will provide a foundation on which you can rely. Meanwhile, you will start learning what your adult stature is likely to look like, and your bones, and connective tissue, and very importantly your endocrine system (which controls your metabolism) will make progress toward maturity. Mark L.

As mark L said, no need to bulk up at all, 11 stone is quite fine, just go prop or something.