Why girls doesn't want me? (Girls only, please)?

I'm 15 years old, medium height (1.70m/5'6") and skinny (45kg/99.2lb). I don't think I look good (just for being skinny!) and I am (too) smart. I like various music styles, ranging from The Carpenters to Paula Abdul, ping through Laura Pausini and Toni Braxton. My hobbies are computer programming (I am a Linuxer, too) and reading. Can you girls describe why my cl' girls only say my name to ask for the math answer? (Remember, please, that I live in Brazil.)