Sorry to hear that :( I HATE the day of the results, ugh... Well, in my experience, my period was "normal" after Prometrium. In my case, however, I never get periods on my own, only with Pills and those are usually pretty light. I thought that the ones I got after failed IUIs (ovulation induced, you may say) were what normal periods would look like if I ever had them, and they usually lasted 3-4 days with minor cramps. Good luck on your next one!