Hi.I am 16 years old and I my penis is slightly curved in left.Are there any exercise?Can my girlfriend and I have normal sex?

There is absolutely nothing wrong with a curved penis. Some men, and mostly women, consider it to be a definite asset.

Yes.. its not uncommon, esp with men who masturbate... and you know you do. A guy who doesn't is likely not alive. And it shouldn't hurt a thing concerning sex.

Sidenote... please use protection... even better, abstain. Not going to get preachy on you here... but I have a beautiful son who was conceived while using birth control and tracking my partners rhythms. Even "planning" doesn't always work...

And the typical teen doesn't have half a clue about fertility cycles. So if you choose to be active, please use birth control.