oh nikkinoo, that sounds terribly hard for you both 
Is she already seeing CAHMS or are the AD's on prescription from her GP?
If she is seeing CAHMS then I think you need to go back to them and explain that things are getting worse not better, and ask what they think the next step should be. Ask for an emergency appointment. Don't be shy: a suicide attempt is not something to be brushed aside.
If she has only seen the GP, then I would go back there and ask for a referral to CAHMS. Tell him it's urgent.
Is she still attending school? They might be able to help with counselling there, and they might also be able to speed up a referral. Let them know what is going on.
In the meantime, keep reassuring your dd, show her that you understand she is in a bad place and that it must be horrible for her, but that you are convinced that something can be done and that she won't have to live with these bad feelings.
My dd took an overdose of antidepressants 10 months ago. She is now back in fulltime education, with a good group of friends, lots of interesting things going on in her life and good hope for the future. She is not cured: she knows she will probably have to live with anxiety and mental frailty all her life. But she also believes she will be able to manage.