chances of pregnancy 🙃

okay sooo. i'm on the pill and have been on it for a little over a month. i'm currently on my period and had sex tonight. we're gonna call the guy i had sex with Tom*. okay so Tom knew i was on birth control and decided he wasn't gonna use a condom. i wasn't worried because i'm on the pill. well Tom came in me and now he's worried that i'll get pregnant. I keep telling Tom that i most likely won't get pregnant since i take my pill everyday at the same time. i'm not worried like at all because i feel like the chances are small to basically nothing. Tom is still currently freaking out. what are the chances that i get pregnant? 🙄