Could I be pregnant?

So I am on Cryselle 28 birth control, and February 20th I had unprotected sex. The following day I was lightly bleeding; I thought maybe I tore something. Then my bleeding got heaver and heavier, and my period wasn't due for another 2 weeks (March 5th). My bleeding continued to be heavier, little different odor, and for the first time in my entire life I had lower back aches. My breasts were tingly/sensitive, major cramping. Certain foods are making my stomach turn. I was still bleeding March 4th, but it was darker, like the rest of the blood coming out. Yesterday, a little dark bleeding still but it has mostly stopped. Yesterday is the day my period is supposed to start. Now that it is practically stopped, does that mean I have missed my actual period? This is unusual for me. The most I get my period is 2-4 days; I have never bleed for 2 weeks. I took a pregnancy test last night and it came out negative, but it was also the day my period was supposed to start. It could have been to early. My lower back aches have stopped, but certain foods are unsettled in my stomach and my breasts are sore/sensitive still. Help.