Sounds similar to my DD. She was diagnosed at 12 and similarly her natural ability level had resulted in her being to hide the difficulties she was having as she'd come up with her own coping strategies.
Her school have been very supportive. They've created a learning passport for her based on the recommendations in the reports. This is shared with all her teachers.
It includes things like extra time in tests and exams, not calling on her in class as her slower processing speeds can put her under a lot of stress in those situations, and providing copies of powerpoint presentations or glossaries of technical terms ahead of new topics so she can go over things in her own time.
She knows if some things aren't happening she can remind the teacher of her passport or can go to the SENCO for support.
A lot of the advice is also about her taking responsibility for her own learning and accepting that she might find some things harder but that doesn't mean she can't do them or achieve as much as her peers. It absolutely shouldn't hold her back from doing whatever she wants. She's developed new organisation and revision strategies which have helped her.
I think just getting the diagnosis was actually really helpful to her confidence and self-esteem. Prior to having the test she'd started saying things about not being as clever as her friends and I knew that wasn't true. The diagnosis proved to her that it's not true, it's just that her brain works a bit differently so she has to adopt different techniques for certain tasks.
I think schools are much more aware of issues like this nowadays and want to support their pupils to achieve their potential. Our experience has been positive. Fingers crossed yours is too. Good luck to you and your DD.