My last period was on 8-20-13. I had sex on 9-1-13. I ovulated on 9-3-13. I'm also on birth control pill. I have been extremely nauseated, feeling light headed and dizzy, left pain of and on in my stomach, gassy, peering more, and I was constipated but not anymore. I have also took 2 pregnancy test and they were negative. Am I pregnant?