ive had four periods, all normal and I've never had sex, so I know I'm not pregnant, because I share a bathroom with my brother who masturbates and I've been paranoid all summer. Plus, when I went to go get a physical, my doctor said that since I was young and just started my period, I've never ovulated yet. I'm 13. I was at the beach on Thursday and we came up to eat lunch. I went to the bathroom and wiped, and there was a spot of blood on the toilet tissue. I'm so freaked out because my period is not due for another two weeks!!!!!! What's going on????? Please help!!