This sounds like a pretty normal phase to me, though for your DSD it would seem to be more complex as she has issues with her DM to deal with as well as all the usual teen traumas.
It is amazing how a perfectly lovely girl who gives you hugs and is polite and helpful can turn into a nightmare seemingly overnight. However the hormone storm that is in their head does affect them hugely and there isn't a lot you can do about it.
When our two DDs have been like this we learned to ignore stuff that didn't matter and stick to our guns on the things that really did matter. Never lose your temper and when they are having a major strop just walk away calmly.
As a new member I am hoping i can get some advice, my 13 year teenage step daughter has suddenly turned into the bride of chuckey she is constantly angry, unmotivated,disrespectful wont engage with any of her peers acts like a 6 year old, wont go to be bed wont get up This is exhausting with no rest as it 24/7 confrontation from her, we have tried counselling and checked that there is no bullying etc. she refuses to see her biological mum and is constantly vile it can feel like survival of the fittest any advice please