I have been off birth control since january of 2008 and trying to concieve. My period has never really been regular except for when i was on birth control. I usually go four weeks between the ending and starting of one. I had my last period on July 24th, it lasted for a week. I had unprotected sex on August 3rd... 4 days after my period ended. Then three days later i started spotting very lightly for about three days. I still haven't started another period yet. According to how my cycle has been i should have started on August 28th. I took a pregnancy test last tuesday and then again this tuesday. They both said no. Does this even sound like it could be a possibility?