Should I take the plan b

Me and my boyfriend had sex on Sunday, they day my period was supposed to come and used protection. My period is now 2 days late and yes I have been stressed about it. After we got done having sex, we checked the condom, just go make sure it didn’t break or anything and he touched the top of the condom, that seemed to have like a thick discharge. It looked like mine from before we had sex because I did have a white sticky discharge during the day. About maybe 5 minutes later he did finger me but we were in his bed and he was touching his sheets so I’m not so sure if he wiped if off. I’ve been really stressed about it and he says he will buy me a plan b, but I’m not sure if I should because I know it does throw off my cycle. Tips pls. I’ve also taken pregnancy test from our recent times of being intimate and they have all came out negative. My percentage of pregnancy was 1% that day