Nope .. am actually quite superstitious but this is one i dont believe at all. I have broken a mirror before and it never brought me any bad luck. Dont worry about it hun.
According to superstistion, it has something to do with damaging your soul and taking 7 years to cleanse the badluck. I have always herd people say 'oh no, not another 7 years bad luck' when a mirror was broken, and now I have broken mine, Im getting kinda paranoid....
I'm not overly superstitious, but I remember breaking one when I was a little girl. I was at a friend's house playing. We had her mothers antique hand mirror and I dropped it. I was so scared of getting in trouble.. I ran home...only to find my mother on the bathroom floor clinging to life. If I hadn't broke it and came home, she would have died within just a few minutes. So, I guess it was actually good luck!