Thank you both for replying so quickly, that's incredibly helpful. I've had a look at the Eva Musby website, bought the book and will continue to read and get started on the family based treatment approach tomorrow.
She is really eating very little now. She gets up early to eat breakfast (a protein yogurt and fruit) before we go down, but I realised this morning that she is flushing it down the toilet. I suspect she has been skipping lunch at school, she used to take a packed lunch but changed to canteen lunches and I can see that she has been buying soup every day since they went back 2 weeks ago (Scotland). But I suspect she isn't eating it. The last couple of days she said she had gone to the co-op with friends and had bought a sandwich, but I'm certain that isn't true. She has been leaving some of her evening meal, and had said a couple of months ago she would like to eat less meat, so I've been cooking much more of a plant based diet. I'm realising this was a tactic to make meals less calorific... and that's basically it. No snacks, only drinking water. It's only been this bad for a couple of weeks, and I've been trying to support her to eat more by getting her more involved in choosing snacks and meals, Hoping a sense of ownership might help, but it hasn't.
She has already had a few blood tests at the start of the month, as she as complaining of being cold when we were on holiday (in a hot place). I was worried she was anaemic or under active thyroid, and they seemed to do a whole raft of tests including those, and all seemingly normal.
I'm just so gutted for her that she is struggling so much, and I feel like I've been hit with a brick in realising how bad it's become without me really acknowledging it until now.
I will find out tomorrow what the expected timescales are, and am really hoping we don't have to wait too long. But I don't think we can wait to get started with feeding her properly. I'm dreading how awful this is going to make her feel initially, and how I will cope with her reactions to it all. She is the most skilled out of my kids in pushing my buttons, so I know this is going to happen and I need to really think about how to manage myself so I don't react.
Thats a whole brain dump. Thank you so much, i can't tell you how much you've helped.