FTM and sooo confused 🤷‍♀️

So I’m 21 weeks 3 days today and ..... here’s the dilemma:

I don’t think I have a short torso but when I sit in a chair or couch I can feel my little one kick and move right below my breast close to my ribs. I know that your uterus is supposed by your belly button so I don’t know if what I’m feeling is even possible. Is the baby really that big now?? (nope it’s not gas. I’ve been feeling baby move/kick for weeks now so I know the difference).

The same thing happens when I lay flat on my back. I’ve googled until I can’t google anymore and I can’t seem to find any info on any of this. So I figured I’d get some advice from “real” people aka moms. Has any ftm or veteran moms felt this? I thought that the ligaments kept the uterus in place and stopped it from moving and shifting sorta kinda