my last full period was february 20. the incident of the unprotected sex was march 1. i took a plan b one hour after the unprotected sex. i had four days of bleeding march 11-15, but i don't think it was my period, i'm assuming it might have been the side effect of the pill. after weeks of worrying i took a home pregnancy test and it came out negative. i'm scared the test may be false because i drank a lot of water before taking it! still no period, i'm really worried!! could i possibly be pregnant?