dear Jessnemo,

It sounds as if you are generalized hyper-mobile. It can be a perfectly normal condition (there are very stiff and very agile people).
It can also be part of a disorder. The amount of agility (hypermobility) can be assessed by various tests.
Was the physiotherapist you went to specialized in paediatrics?

I do suggest you go to a paediatrician and have yourself assessed especially because you are also telling us that your back is extremely curved.

Good luck Esther