I have had psoriasis since I was 2, I am 40 now. I remember the comments as a kid and being covered in tar like creams etc.
I still have it and am currently experiencing a bad flare up its a chronic condition unfortunately!
I would say I am a confident person now and the psoriasis has not affected me other than to have perhaps more empathy and to be more sensitive to others. The comments bothered me a bit As a kid and I was shy so did get embarrassed. They were infrequent though and tended just to come from the ‘naughty boys’ in the class who would say stuff to well get a reaction, I ignored them and they stopped very quickly,
From my mid 20s I got more confident and now I just explain things if anyone asks about my skin (it very rarely happen now though)
I think that the most important thing is to get her mentally strong. If she has autism this may be more difficult but getting all our youngsters to recognise that what we look like is the least important thing compared to intelligence and personality traits I think is so so important.
In terms of treatments there is no link whatsoever with diet and psoriasis unless she also has coeliac disease. Then a gluten free diet may help a tiny bit. If she does not have a gluten intolerance it will be of no help. Psoriasis is an autoimmune disease and often genetic so do not worry about her diet or feel that you are doing something wrong by not getting her to eat certain things. You are not.
The only things you can do to try and minimise flares is to minimise stress, ensure plenty of sleep, try to keep her healthy as much as possible to avoid infections as these can all exacerbate the condition. Even if you do all these things likelihood is the psoriasis will still be there however!
Have you seen a dermatologist? If she has moderate to severe psoriasis UVB phototherapy usually works amazingly well. And often will clear things for sometime. I have reached my quota on this now having had a number of light treatments over the years but it cleared it up every time for me. its 6 weeks of treatment 3 times a week so time consuming but I achieved 100% free psoriasis each time,.
I personally found aveeno worked better than any other topical creams (though stopped working after a few years). The steroid creams etc thinned my skin but rarely did they make much difference. They tended to have an effect for the first 2 weeks of using then the psoriasis would start to flare up worse than it was before starting them,
It is definitely worth keeping a diary to see if the creams are actually helping. If the steroid ointment is not helping stop it it does thin the skin and a lot of doctors do not realise how strong the steroid in dovobet is. There is no long term risk known for topical treatments in terms of growth, child bearing etc. It’s more the thinning of the skin which can cause problems in later life.
Try not to get your daughter involved in this too much though and I’m sure you are doing this already but never let her realise it is effecting you. It’s not nice but there are way worse things people can have and its never stopped me from doing anything I want to do.