copper iud

Hi! So I need serious answers! Last night my boyfriend and I had sex for the first time since I got my copper iud inserted a little under 3 weeks ago. (This is where it gets graphic) we were so so stoked to have sex that I let him "come" inside me completely. I started crying after bc I was so so terrified that in that moment he could've gotten me pregnant. Has anyone else had this experience, if so, what happened? And should I be concerned and what procausons should I take next time other than using a condom. Thank you!