I believe you just excite to easily, it is very common in younger men. You can learn to control it as life goes on, but all you are doing is pre ejaculating. You enjoy what you see and your body is reacting to it. It is also more common in guys who are not circumcised. Not that it makes any difference.

You're body is changing and what you're going through is normal. Just take each day as it comes and enjoy life.

It is nothing to stress about matey.