Is there something wrong with me? If so what should I do?

I have mind issues. I can't concentrate. All I think about is guys, sex and babies. I don't know what is going on. I lost interest in playing my viola and reading a book is a struggle sometimes. I hate my mind when its like this, it has been this way for a while. I yearn for a boyfriend. Just someone thinking I am beautiful and actually willing to touch me. That is a wonderful thought. I can't find any friends. I have nothing in common with anyone. I find conversing useless. My sister says I am selfish only bringing myself up in conversations. So I avoid talking unless I absolutely must, like in front of my mother's friends. Everything in my life has changed for the worst. I am as lonely as I have ever been. Relationships with family and friends are not very close and are gone. I feel obsessive because all I have been thinking about is this one guy. I never talked to him but I wanted to. I hesitated and that was probably my biggest mistake. I truly thought we could of been together, but that I think is out the window. The thing I want most is just to be in a relationship when I should be worrying about school. I feel stupid and lost. I feel like I never say the right things. I don't know. Just respond to me please. I need some advice.