My dd is just over 6 months and while very wriggly (in fact more wriggly than any other baby I've met of the same age?) shows no interest in moving from whatever position she's in, unless it's her front in which case she cries. So she'll happily sit on my lap and swing backwards and forwards vigorously, and kick around while lying on her back, but is not interested in rolling over or trying to get to a toy out of her reach. I do try tummy time but she gets very upset very quickly, and trying to entice her to move by holding a toy is just met with her losing interest and turning away. I wasn't too worried as she engages well with eye contact, responds, laughs etc and seems strong in her posture and limbs but the mum of a baby born the same day as her posted in a messaging group I'm also in saying her ds sits independently, bottom shuffles, rolls around and balances on all fours, trying to crawl. So I'm a little worried now!