Hi Currymaid.
DS has hypermobility syndrome. I didn't discover it until he started physio at 14 months old.
Similarly to your DD he didn't do anything but sit and when he eventually started to move, it was a bottom shuffle. I wasn't overly worried about that, because DD was a bottom shuffler too and went from that, straight to walking at 11 months.
DS bottom suffled, but wouldn't weight bear on his legs at all, didn't like physical games like that.
When the HV did his 12 month check she said she would refer him to the physio department just to put my mind at rest regarding his not weightbearing or standing while supported at a table or anything.
He had his first physio appointment at 14 months and straight awy on their assessment they said "yes, he is hypermobile, he is super bendy".
She showed me how happy he was about being bended into a small ball which is one of the signs of hypermobility. Is you DD comfortable to be folded up like that?
Physio went very well and he was walking the day before his 19th birthday, so while it was 6 months later than most of his peers, it was still within the normal range.
It hasn't affected him much since, he has good core stability now, a good by product of your joints being bendy. The HV said that people with hypermobility make good ballet dancers and gymnasts. He's not in to either of those, but now he is 3, he does all the things normal 3 year old does, like ride a trike, climb a climbing frame, jump, skip, hop, dance, etc. There is no difference there.
My advice would be to tray and stay as calm as possible about it. Hypermobile or not, all children develop at different rates and are always learning, so you might find that even though she is slightly behind peers physically, she will be doing well with her speech sooner than they will. It's all different.
Speak to your HV at her 12 month check and ask her to take you seriously in your concerns. If you want a physio assessment then it is best to be forthright and demand one. The worst that can happen is that the physio says your DD is doing just fine, it won't harm her to be assessed.
Having said that, I know plenty of babies who are not interested in moving and are quiet happy to be waited on by their mummys. I'm sure your DD will start to get a move on when she feels ready.
Good Luck