Goodness what a dilemma !
Its an awfully big ask to need to change your DD behaviour in a week and must be so hard doing for a year what she thought was right only to find she wasnt 'doing it right' all along. Im sure someone should have mentioned this before now and it comes to crunch time !
There's 2 years between my DD's and they struggle to communicate at the best of times ( ho-hum ) so to be with children 4 years younger when she is, I'm presuming a teenager, must have been incredibly difficult - she sounds like a beautiful caring young lady but I think the school have let her down in not picking this up sooner.
She must have potential for them to have taken her on so I'd be looking at somewhere that wont leave her floundering in the 'baby class' and maybe help her with private / one to one tuition to help her catch up instead of her having to change her whole personna for them.
Im dont mind my DD having to 'fit in' but not if it means she has to change her whole peronality to fit in.
Blimey, my DD is having a daily identity crisis at the minute so a massive

to your DD for copping thus far.
Sending huge hugs to you and her for the right decision and the right outcome - please let us know how she gets on xx