I got my periods on 16/9/12. I did not get my periods in October. I didn't have sex during September. But I had sex with my boyfriend on 19/10/12. I had already missidd my period for that month before we had sex. We had unprotected sex and not sure if he finished inside or outside of me. I've still not got my periods. I took a home pregnancy test a week ago and it was negative. Could I be pregnant? If so what are the chances of me being pregnant?