I had unprotected sex three weeks ago with ejaculation. I got my period on time however, it was heavier than usual and only lasted three days compare to 5 day (which is has been the same way since i got my period). I had a lot of cramping before, during and after. I'm moodier than usual and irritated. I also took a home pregnancy test a week ago and came out negative. What does this mean? Should I be worried?