Sitting is getting uncomfortable😩😆

I'm 33w4days and it's officially starting to get uncomfortable to sit on a couch/ in my car for too long. I'm carrying pretty small so I'm not with a bigger bump but maybe it's the extra weight from baby growing? I don't know but oh my godness if I try and sit for too long my lower back aches (only when sitting for long periods) and I feel like one of baby girls body parts is lodged in my ribcage🙈. Anyone else?