ON june 24th i started taking birth control a week later on the night of july 3rd and the morning of july 4th i had unprotected sex with my boyfriend i was suspose to start my period on july 10th but my friend said that since im on birth control she said that i would start my period when i took my white pills which i am into my forth day of my white pills and i still havnt started my period it is now july 18 could i be pregnant