Hi I have inregular periods and I had a period in June 2 went to see doc around the 14 and do 3 pregnacy test every 2 weeks after July 16 and nothing today it said neg and I has intercourse with my husband last night and I had light bleeding what could it be I try to check my self since I am taking phentermine to lose weight but Im not using birth control since its hard for me to get pregnant !