Hi, I am 16 years old. I play most contact sports, football and wrestling. I am having a problem building muscle. I started lifting at 15 nothing heavy from where I was young. However, I have not gained any muscle mass. I take protein of the mornings and 20 minutes after I lift. I'm on a school workout plan. Can someone please help me? I am getting very frustrated and discouraged. The person I lift with is seeing excellent results, but I seem to not see anything nor get stronger.