Please don't worry. Its going to become a habit, and you won't be able to stop it. Just relax.
Boys are going to trouble you for the rest of your life, so don't worry about them either. While you're young, you shouldn't have to worry about them, you'll find him someday, even if its not in the way you expect.
Just be yourself, don't worry about how you look, or if other people judge you, if they do, then they're not worth thinking about.
Friends come and go. While you may think that you'll be friends with them always, that's not always the case. They leave, as many people do, but in their place better people will come.
I wish I could tell you this, and make things easier for you. If only you knew what I knew now, then maybe you wouldn't have worried about the little things so much.