im 20 years old and 5 1 and im 160 lbs , no serve medical history only a miscarriage last year, my periods have been regulary coming on the 17 of each month since july 2010 until this year in march, the 17th came around and yet no period, it is now april 16 and still no period, i cramp, back aches, spotting, and have to use the bathroom fequently and sleep like there is no end. ive tooken a pregnancy test since then and its came out negative, is there a chance i can still be pregnant?