Will I Conceive After Taking Unwanted 72 And Having Menses?

hello mam , we had inter-course in dec just after my periods and than i take unwanted 72. .and my period was came within 6-8 days but after that i had 2 missed period and little spot is occur but my HCG test is negative.... is there any chance to get pregnant. . ??? and if any than how conform it. . ??? plzz help. .