I can understand your concerns regarding th efrequency of masturbation.. I went through the very same thing when I was your age and even today (now 27). Trust me it IS normal, but I wonder IF my frequency of masturbation (still 3-4 times a day) is considered normal?
Masturbation during the teen years is a very normal behavior. It only presents a problem when it interferes with developing normal social relations and when teens rely on it excessively to relieve tension. Masturbation does not in itself damage the penis or testicles. If you have concerns you'd like to discuss with your doctor, ask your parents to arrange an appointment. Tell them that you'd like to talk with the doctor about some personal concerns.