around feb 15th i had unprotected sex, i thought i maybe pregnant bc i was ovulating but i started my period a few days later. i started my birth control that sunday. it made me feel sick so i stopped. every since then i still felt sick, and i realized today im 4 days late on my period. i took 2 pregnancy tests prior of starting and they were negitive. is my birth control still messing with my period, or were they false negitives!?? idk what to think?!!!