I had sex on Jan 25 and took the morning after pill the same day. My period came Feb 4, seemed real but I thought it was 4 days early (which could mean my ovulation was actually around Jan 25 and the pill would be too late to work). I had sex again on Feb 14. Ultrasound on Apr 28 put EDD at Nov 8 and LMP at Feb 1. So I was confident that Feb 14 resulted in the pregnancy, but now I am questioning that period based on things I've read about the morning after pill. Does the embryo development start at fertilization or implantation? I.e. could Feb 14 be implantation date and not conception date?