Suggest Remedy For Delay In Periods

Hi, me and my boyfriend had sex on the 1st and 2nd of august and i was suppose to get my period on the 3rd and i did, which didnt worry me but ive been reading things. I dont know what my chances are of getting pregnant, i take alysena 28 ive been on it for 2 months and he had a condom on but it fell off for a breif second, he didnt ejaculate in side me but im still worried. I need advice