Should I get a plan b or risk it ?

I had drunk sex with my ex last night. My dumbass didn’t use a condom. Now I’m not sure if he came inside of me or not. I kept asking did u he kept saying “Idk I don’t think I did” He was still hard and i didn’t feel it oozing out of me only thing on his 🍆 was my wetness so i don’t think he did. Not sure if i should get a plan b cause I don’t want to waste my money plus it pushes your period back. I don’t want my period in my birthday but I’m almost done with college so I don’t want to take the risk either 😢