I posted early on in your thread, and I'm going to do so again just to contrast your experience for anyone reading.
My dd got her block braces on a Friday morning and was asked a question by orthodontist as soon as they were in.
I couldn't understand her answer and loads of drool just fell out of her mouth and down her chin.
She looked so different, I was shocked but hid it.
We left for school after the "wear them constantly" talk, but as soon as we got in the car I said she could leave them that day and start at 4 when she got home, as she was pretty upset.
We did just that.
She talked constantly for 2 days, and had to learn how to swallow but by the Monday was left with a small lisp only.
There was some jaw ache, eased with paracetamol, and a couple of ulcers too, but on the whole it wasn't too bad for her at all.
We took photos every 4 weeks and the difference between each was HUGE and a massive motivator.
She did 6 months block braces and then onto train tracks which are due to come off mid-december.
These too have caused mild discomfort at each tightening for 2 days.
I'm sorry your dd has struggled so much, but I just wanted to offer the other side of the experience.
A huge well done to your dd for continuing with her treatment!