Help I’m worried

I think I messed up. Me and my bf have been together for almost two years now. He is 19 and I’m 17. We have an active sex life. I got my nexplanon taken out Monday and started back on the pill yesterday (sunday). U have to take a full pack for it to control birth lol. And me and my bf had sex yesterday and usually we have unprotected sex. But now I’m not on anything but 1 day of pill we put a condom on half way thru. It started slipping so I pulled it off and then I realized it was slippery bc he had already came. I’m worried that while it was slipping it could have gotten inside me. I dont know how common this is or if I should be worried bc I dont really ever use condoms. (He was my first and maybe even my last) we didn’t use condoms while on nexplanon because we were in a stable and healthy relationship for a long time. Which is no excuse. But I wanted to make it clear that I wasnt having unprotected sex with anyone.