Late diagnosis of hip issues??

[JimmyJam2019]

Have a GP appointment later in the week but thought I'd check in here too.
My dd is 11.5mo. She doesn't walk, crawl, pull up, rarely rolls, just sits (which she did easily from 6mo) and only if you plonk her down, can't sit up from lieing down. If I hold her to stand up, her feet are flat and taking some weight but I need to hold her up or lean her on something or she'll keel over and not correct herself. She won't move her feet, her legs are locked.
Anyway, I have noticed that her right thigh is straight up and down whereas her left thigh has a large crease. I know uneven creases can be a sign of hip issues but maybe she's just a bit slower. Her speech, social and fine motor skills are great for her age. Thoughts? Similar experiences?

What does she do then? Lay down? Is she crying? How is her tummy time? Is she trying to push up?

Not sure about leg crease (surely depends on how chubby the baby is), but the lack of movement is what I think is a bit of an odd one out here, not her non-walking/weight bearing.