Pregnancy w/ Anal?

So recently me and my boyfriend tried out anal sex. It was good and all, but we went back to regular sex using condoms. Recently we ran out of condoms and have no money to buy more so we tried out anal sex again. Do any of you know the chances of getting pregnant if they cum inside and it drips out into the vagina? I was on my period so I had a tampon in and I would take it out afterwards in the bathroom, but there could always be a chance you know? If anyone has experience with this I would love advice. Thank you ❤️