Deep sex

So I was having sex with my boyfriend (I am female) and he was reallyyy deep. I could feel my insides moving, and when I looked down I could see something moving too. Like and organ pushing through my skin or something. (Lower stomach, between hips). It’s like his penis moved something.

I know that sounds very drastic but wasn’t as bad as it sounds. Just wanted to see if it’s happened to anyone else?

Ps, I am slim, with low body fat on stomach