My daughter is 10 and also has had severe eczema pretty much since she was born. We've been referred to dermatologists three times on the NHS and have seen two privately and, in my experience, they both give pretty much the same advice and are only able to prescribe stronger steroid creams and emollients.
Unfortunately, I don't think it's just one thing that causes the eczema, or at least that's what I've found, and it's just a matter of trial and error. After years on a waiting list we managed to get an allergy patch test which has helped a bit but I think stress/tiredness, change of season, humidity and eating too much sugary/processed food aggravates it too.
My daughter tends to overheat when I apply thick creams so we've found that lighter creams work better for her than ointments, and I don't apply them just before she goes to bed as she overheats which makes her scratch so I make sure she puts the last application on at least an hour before bedtime.
She also wears her hair in a high ponytail in bed as she said that's cooler for her and doesn't tickle her back making her scratch. Most nights she goes to bed with an ice block covered in a towel to cool her hands and feet down - they're the most itchiest parts of her body.
I give her a bath in dead sea salt once or twice a week. I'm not sure if that helps much but it is soothing.
We also don't use any other products apart from Dove as that doesn't seem to cause her any problems.
I also make sure that her bedding and, as much as possible, her clothes, are 100% cotton.
We did try giving up dairy and gluten for a couple of weeks but that didn't seem to do anything so reintroduced it again, however I did keep a food diary and, by process of elimination, found her eczema gets worse after eating citrus fruit and grapes.
I also bought her a "fidget spinner" as it helps to distract her so she didn't scratch.
When we were put on the waiting list for the NHS I kept phoning up every so often to see if there was a cancellation and managed to get one so might be worth doing that just in case your daughter can get seen sooner.
I hope your daughter's eczema gets better soon and you manage to get to see a consultant sooner rather than later.