There's nothing wrong with that at all. My boyfriend was that age, and in the same situation...and then we met and it changed. Sure, it's not going to be a marathon...but don't be nervous. A good girl will have no problem if you barely even get in there before you're done. She will wait, and be patient and you will learn and get better and better.

On a side note, I maintain that guys who are still virgins..no matter what their age...are the nicest guys you could find. They are still pure. Not looking for the hottest young ass to walk by.