should i take plan b

so i had sex last night and he finished in me and i am on birth control and i take it as i’m supposed to (some days might be an hour later than my regular time but never more than that). no one has every finished in me before so i’m kinda scared and i just want second opinions on whether or not i should take plan b. i know it’s bad for your reproductive system and they say to take it only it you have to... thoughts?