Am I depressed as an adolescent?

I have never saw the bright side to things all my life. Through my childhood I was quiet and I refused to talk until 3rd grade. I was lonely when I was a child but I don't remember being depressed. Now that I'm in high school, it seems as if everyday is the same. Everyday seems dreary, I never have a spark of happiness. I am lonely as well, I don't associate with anyone during lunch and the weekends. I'm in a lot of clubs such as Seekers and Yearbook, but everyone just doesn't seem interested in me. I have a boyfriend and he is the sweetest guy I have ever been in a relationship with. But sometimes, he doesn't like my depression and feels I'm always sad everyday and rarely happy. I feel bad for him because he has to deal with my abusive temper and my depression. I guess I am bipolar too, I could be overjoyed and then if something angers me I end up hurting someone. I'm a 15 year old girl. Suicide crosses my mind often. Every therapist I visited just didn't help because I feel rather uncomfortable talking to a stranger about my problems. I also despise of the majority of people in my school because they're all just backstabbers and gossipers. Is there anything I could do to stop this depression?