Teenage years are never easy, especially as you are busy trying to define yourself. If you find yourself in a whole you cannot climb out of, please go see a psychologist or psychiatrist you can talk to, and they can really diagnose you and if necessary prescribe medication to make you feel better.

As a teenager I became very withdrawn. My horses were the only thing that mattered, and luckily I found school interesting, so I paid attention in class. At your age friends are very important. Please don't make your boyfriend the only and most important thing in your life. You need diversity and a social aspect to your life too. I'm only 24, yet all my friends, as well as my boyfriend, are a whole lot older. The people close to me also don't look at me as a typical 24 year old - because I really am not - but this is because I've proven myself and they know me.
Don't let others' opinions of you bug you. Set yourself goals (short-term and long-term) and drive towards them regardless.