What Causes Light Vaginal Spotting And Abdominal Pain After Having Unsafe Sex?

HI, I had unprotected sex the night of April 8th and April 11th. I have been documenting my period for the last 8 months and my cycles occurs about 26 to 28 days. I was supposed to start ovulating April 13- April 17. I had an ovulated kit and I did it every day for two weeks starting April 13 and I never ovulated. On April 17 I spotted but not every time I went to the bathroom. Since April 17th I have not had any spotting or a period and due to my calculations I was supposed to start April 30th. It is now June 9, 2015 and I have still not received my period. I went May 15 and got a blood test done and it came back negative and I have been taking at home pregnancy test every week and they have all came back negative. I have been getting headaches every day for the last month, and I get lower stomach and back pains like I’m about to start. I have had to change deodorant that I have used for over two years because the smell makes me sick. I also have been getting sick almost every night before bed. My boobs feel extremely heavy then normal and I can’t fit into most of my sports bras. I also can’t stand chocolate but I have been craving it almost every day. So my question is, even though I am getting negative at home test is there still a chance I could be pregnant?