Welcome to HealthcareMagic Forum
First thing to remember that masturbation
does not cause worn out and you can masturbate 2-3 times per week without any adverse consequence.
Second you are in the pubertal age group and lots of changes occur in sexual organs under the influence of hormones during this period like increase penis size, hair growth around penis etc. But in your case changes appear to opposite so consult general physician as soon as possible.
Wish you Good Health, www.99doctor.com