If I said it will get better I doubt you would believe it right now being so low but it does :)
Going to the GP was a good move keep on demanding the support and contact the relevant bods like Mareeya has mentioned.
Think of some strategies you can put into place when these meltdowns occur that may help you and her in the meantime. If they are escalating to such a degree maybe a safe room may be a good idea?
When school was hellish for DS and consequently anxiety attacks loomed once he walked in the door from it I had emptied his bedroom and left nothing but his bed and a million and one cuddly toys in it plus a few cushions. He could then throw these as much as he wanted to without causing harm to himself.
If things got to the extent there was no calming him I placed him in there and shut the door and sat on the other side. There were no locks just me sat against it. It helped for loads of reasons.
He couldnt see me or the rest of the family but knew I was there outside. and it helped him to calm down a lot quicker.
It gave me the option of being able to keep on quietly repeating to him the same sentence ie. when you are calm for 5 minutes we can talk.
I was calm as I couldnt see him either and could focus on the wall oposite. DH used to bring me up a mug tea so in a way we were both getting well deserved time out :)
I found with a door in between ds used to talk his issues over a lot more calmly than having eye contact with anyone or any distractions.
Its not a quick cure by any means and sometimes I would be sat there an hour or more but at some point he would become exhausted and then we could chat. This way was good for us as I was not compelled to keep on trying to explain things (mothers habit) in between telling him not to climb this or throw that or shout etc.
I never punished him afterwards for the behaviour in his room as the majority of his meltdowns were due to control issues at the time which he could not help and we knew his stresses were entirely school orientated at that time. We merely hugged and put the toys back lol.
Over months he learnt to take himself of to his room of his own accord.
Its hell and I really do sympathise with you and your DD. But stick it out and turn your upset into a manic mission of forming a plan of action 
It WILL get better.