I'm really sorry to hear about the struggled you're all having at the moment. I've experienced this from both sides so I know how challenging it can be.
I lived with my sister who battled with an eating disorder for years. It placed so much strain on the family that I moved out with her to try and relieve some of the stress my parents were experiencing. It was a really challenging time because I knew what was happening with her and her ed and she knew I knew but she was also so sick that it was like it didn't matter.
I've also now experienced this from the other side, having an eating disorder myself. It's so tricky because sometimes there is a rational part of my brain that knows what I'm doing isn't healthy or right but the bigger and louder part tells me I have to do everything I'm doing. It's a constant battle.
The fact that you're getting her into therapy is a huge positive. Even though it's not for a month it will be worth the wait. In the meantime, Butterfly is an amazing resource. They offer phone and online chat support, a database for finding professionals and so much information. They might be useful for both yourself and your daughter. This time of year is particularly difficult when it comes to having an ed. As stressful as it feels for you, it's also extremely stressful for your daughter. I know it isn't easy but as much as possible, avoid any conversation about food, eating or related behaviours. Your daughter will be well aware of the ed behaviours she is engaging in however having these pointed out will likely make her feel much worse.
I really do have so much empathy for how tricky this situation is for you all. I hope you can get through the next few weeks without too much trouble while waiting for the therapist appointment.
If you have any questions or want to share any frustrations, please reach out - I'm here for you!