Ok so I'm gunna show you my calendar and the days I had sex I got off birth control on the 10 of July now since I was on birth control my periods would come all different each month sometimes I wouldn't even get it.. Now I thought I wasn't gunna get it this month but it came so late.. I'm bleeding a lot but it's light not  ark.. Could this be implantation bleeding or just my period I took a pregnancy test today but it came out negative so confused. I also had cramps today so what could it be??