@Concerned-Mum As someone continually in recovery for alcohol use, I totally get where your child is coming from unfortunately. Drinking helps in the short term to deal with things, but it ends up then becoming a way to cope with everything, big and small, and then there's the tolerance you build up over time, which means you have to drink more to get the same effect. Unfortunately just stopping drinking isn't the answer. It can also be physically dangerous if not managed medically during the withdrawal period, and actually can result in death. i.e. I definitely do not recommend she just stops drinking unless she has been given diazepam and has guidance by a medical professional. In the short term, I have found going to detox and a rehab period has helped me to get physically well, but the work when you leave is very long term for the most part. It's about creating a whole life outside of alcohol where you actually have to face up to your demons and not self medicate it. That is a long journey, but completely doable as well! Seeing a psychologist regularly to work on healthy strategies is also helpful (maybe some family counselling could help so you can go together?)
I can only imagine how stressful and anxiety provoking it is for you to know what she is doing. I guess maybe a longer private conversation between the two of you where you both share really honestly with eachother about your feelings, and the changes you have noticed in her etc could be a good starting point depending on the closeness of your relationship. I guess I would just say, it isn't as simple as "just don't drink". I'm sure your child wishes that for themself as well. I mean, no one wakes up one day and wishes they were an alcoholic.
Sorry I can't help too much with what you are going through as a mum, but let me know if there's anything else you have questions about or if you just want to talk here further.