He doesn’t know if he came in me or not 😰

My bf and I use the pullout method & im on the depo shot. I can’t take pills cause I’m forgetful so I figured the shot was a better option for me. This is my first month on it, probably the second week now. Last night we got a little carried away and he thinks he might’ve came in me a little but unsure. Should I get a plan b?