Uh oh. Help!

So I am 5 weeks postpartum and lastnight my fiancee and I got a little bit tipsy and things got a little heated 😋 he pulled out but he came right on the outside of my vagina. I have not yet had a period and completely stopped bleeding from giving birth around 3 weeks pp. I ran to the bathroom and tried to wash it all off. What are the chances of me getting pregnant so soon? Should I get the plan b pill?? HELPPP 😣😣