im taking pills regularly but this feb.14 '09 i don't have any bleeding.. now im 2months delayed.. i've consulted my OB gyne he gave me provera for bleeding as my ob gyne said.. but still no bleeding.. i've done almost 10 pregnancy test all come up negative.. i've done trans-vaginal and the doctor said im negative.. what is the cause? am i hormonal imbalance? or something??