Pretty much the only thing you can safely use at that age is anvar and only at low doses. Doctors regularly prescribe it to young people and people with HIV or wasting syndrome to gain muscle and weight. By low dose I mean 40mg a day or less, a doctor would most likely prescribe much less if you came in malnourished and underweight. At these low doses you will gain if you are below your potential and eat well, you will be very close to known doses with medical studies to back up the side effects. Anvar is hepatoxic but at low doses will not cause any issues for healthy males. It's also not exactly suppressive since you are just maximizing your natural testosterone by stopping it from binding to SHBG which maximizes free test, over time it will slow down production since your levels will climb. But having a full blown shit down is essentially impossible since you are not adding test.

You will not gain very much on Anvar only so it's not really worth it unless you really need to gain a few pounds. When I was in high school and college it was a pretty popular PED on the sports teams but far from something you would use bodybuilding.