Oh gosh, your poor DD.
Mine was very obviously dyslexic from early on, but couldn't get the formal diagnosis till she was over the age of 7.
She spent most of primary failing everything and thinking she wasn't clever because she couldn't do what all the others did - despite school being brilliant at trying to bolster her confidence.
What really worked for us (and some of these will be more useful as she gets older):
Teach her to touch type as early as you can and move to using a laptop for everything - then they can have spell check enabled and it makes a massive difference in terms of content produced.
Worth trying Toe-by-Toe. Some children can be taught to spell - for others it seems to be utterly impossible. DD is in the latter category.
Be careful which secondary you choose. DD's basically ignore her inability to spell and creative punctuation (even with spell check it can be very odd to read) and just mark her on the content. Some schools are more insistent on accuracy. A sea of red pen is not great for confidence. DD is in top set English despite her dyslexia.
Audio books, films and reading pens are all worth using. DD doesn't like reading pens, but her vocabulary is great thanks to watching vast numbers of decent films from an early age. At 6, I got her onto the Narnia films, Five Children and It etc and by 8/9 she was watching things like Peter Hall's Midsummer Night's Dream and To Kill A Mockingbird.
Lots of theatre trips - basically anything where they can absorb words in a visual way without having to read it.
Ask school to buy in dyslexia friendly reading books (or buy them yourself). There is nothing worse for a child than having to read "baby books" where the content is totally out of kilter with their age and interests.
Massively push anything that they excel in outside normal curriculum. My DD turned out to be very talented at music and performing arts. She landed a secondary place via a music scholarship, does huge amounts outside school and is planning on music college for 6th form and a career in that sector. It has hugely bolstered her confidence and self esteem and nobody cares that she can't spell as it's clear that it's never going to matter. (Plus a good 80% of the adults she works with in the industry as as dyslexic as she is or worse!)