There is not much you can do to regain the length you said you had a one point. There is nothing much you can change at all. I think being depressed over your cock size is a moot idea because it cannot be changed. Maybe you need to learn this before you can go ahead and loose your virginity. You're working with a population of people here that for the most part enjoy large cocks, so looking for girls off this site probably isn't going to cut it for you.

The only thing I can think of is that at 13 your cock looked much bigger on your small frame. I've yet to hear anything about a cock shrinking though.

There is not much I can suggest for you, other than go out and just have sex, things will fall into place and you will find someone who will enjoy your cock the way it is.