will i get pregnant?

i had sex last night on my period and i’m supposed to start a new pack of the pill tomorrow but i can’t get it until a week later. we used a condom. a little bit of precum got on my tampon string before i took it out. or on my vagina but i don’t think it got inside because of the tampon. will i get pregnant? i’m really scared. will i have my period for the next week?