I have a unprotected sex with my b.f on 24-25 july. I have taken i-pill within 30 hr. After I get a little bleeding from 28 july to 4 aug. Bleeding is very little. I have my last period on 18 july. I suppose to have my period on 14-15 aug. I have not got my period till now. What could be the problem. I have already taken pregnancy test that is negative. Please help I am very much worried as I am unmarried.