First, learn to correctly spell "muscle". BMI is body weight and is not necessarily the same as muscle. It is normal to have a small amount of breast as a male (especially if you are a teen). It is called "gynecomastia", and happens to half of males. Actually, you are kind of impressive (compared to most people) for your lifting. Remember, do not fatten up. The point is to gain MUSCLE, not fat. Eat more protein and work out often, but do not overdo it. Try talking to your coach.