13w 5d movement??

Is this possible? I am a FTM, so I heard it's unlikely to be movement from the baby, but it feels more intense when I lay on my belly, or when I am sitting very still. It feels like little twitching with a mixture of weird bladder pressure?? I don't know... If I didn't know any better, I'd say it feels like my bladder itself is full and twitching. Just curious if this description rings any bells to people who know what it feels like, unlike me.

I know it could be gas, but usually I feel gas travel and this doesn't travel, and it stays in the same weird "bladder position."