Lozzy I am like you I have flexible joints but the muscles are tight so I have to see an osteo regularly and go to the gym to loosen and straighten everything out. My knees and back are then worst I struggle sitting still for long. Dd1 was diagnosed this year it's only mild though .her muscle tone is pretty good, she swims and did dancing for a couple of years. She has trouble sitting still so we are working on her gross motor/ coordination to help. Apparently as it develops it will improve her ability to sit still. She prefers to sit in the w position, she had hip dysplasia as a baby and it's common for them to sit that way. It's only now st the end of the year that she is sitting cross legged.