About a month ago, I had an ONS with a girl I met off Tinder. She was menstruating very heavily but we decided to have sex anyways, and I ended up ejaculating inside her.

Fast forward to today, she texts me out the blue and tells me she's pregnant. I asked her if she had had sex with anyone else, and she said no, but I have a hard time believing that she's telling the truth.

What are the chances of somebody getting pregnant while menstruating heavily? I've done this many times before and have never had an issue in the past until today.