chance of pregnancy?

reba

Ok guys I need help. I had sex with my boyfriend on the 20th. Unprotected he started in my vagina for like 10 seconds then moved to my ass after remembering we didn’t have a condom and finished in my ass. I was 4 days away from my fertile window, should I go get a plan b? I know he finished in my ass, but what are the odds that I get pregnant from him being in my vagina or cum dripping down into that general area? calm my nerves.