COULD I BE PREGNANT?!

Ok so yesterday I had sex w my fwb and we did it raw bc were stupid and didn’t even think about it but I thought my fertile window ended but i still had 2 days left. The app told me I had a 22% chance of pregnancy but he didn’t finish inside of me but idk if here was any pre cum in me?! Idk I finished him off w a bj BUT IM STILL SCARED?! Should I buy a pregnancy test or something?? I can’t afford a plan b Rn so plsss just comment !!