Hi Simsam have your dd been referred to the ED Camhs team? Normal Camhs won't be much help although it's good they arranged bloods etc. How olds your dd?
Family based treatment (FBT) is the treatment for children/teens that have anorexia (which it sounds like your dd has developed) this means you take full control of all meals and snacks. You buy the food, you prepare the food and you give the food to your dd. She gets no say on any food related decisions and she has to eat it.
She must eat three meals and three snacks a day.
I won't lie - its hell, your dd will hate you, she will scream, she may become violent, she may self harm and threaten suicide but the bottom line is she has to eat.
You can use whatever leverage you have, so her phone, going out, seeing friends etc.
If she still won't eat you take her back to a&e and ask for the full assessment again. Every day they eat less than 500 cals is a medical emergency and teens can deteriorate health wise very quickly.
The aim is to get them weight restored and mentally they should start to improve as well.
The fb group EDSUK is useful for more tips on getting them to eat as is Eva Musby who has a book as well as information on YouTube. BEAT and Feast are also useful resources (ED charities.)