I couldn't agree more with the sentiment of your post. Hopefully between school and home this young ladies issues can be resolved, though it may be more than a simple home/school problem, hence my earlier reference to CAMHS.
Shame you feel I am blaming school, only seeing it as my experience where the school SENCO told me an issue we were having with one of our kids was a home issue and nothing to do with school, so excuse me if I felt let down.
The problem there is the young lady in question isn't having meltdowns at school. I know from my own experience it is difficult to get school to fully engage when they don't see it as "their" problem.
I've only read this far so far and believe a visit to the GP is a must and hopefully a referral to CAMHS. You daughter clearly has a problem that can't just be explained away as anger issues. Someone obviously touched on autism and Aspergers earlier, but to be honest there a million and one...