Do you think I am Bipolar? Help!?

Am I Bipolar? Ok. So I have been really down. I was bullied a lot this year, and have been down. I had the question yesterday. Am I bipolar? I am 12 and I have been crying alot, and thinking about suicide. My mom doesn't believe me, but I think maybe something is seriously wrong. I have been thinking about sex lately. I'm nerves alot and angry. I am not really tired anymore, and I can stay up longer without being tired. I've been in sports lately, but I think, this won't help my weight. Also, I've been thinking about cutting myself. Whats wrong? Can someone help me?