I'd also add (as a PP said) that's its not just a reading/writing issue. It's a whole host of other sensory processing issues as well. Neither myself or my DDs are good at recognising that time actually passes! We have to have a visual reminder of a deadline.
We can also get totally absorbed in a task & not notice anything else (including a teacher giving verbal instructions). I'm hopeless at maths, but can read a book in day (my particular form of dyslexic is more spelling/maths/organisation). Neither of my DDs read well but the eldest is good at maths, whilst my youngest still writes her numbers back to front at 17.
Crossing busy roads is really difficult for them. They had NO ability to judge the speed of cars or to work out left & right. We did a great deal of practice before they went to secondary school. It's sounds a bit over protective but I was really worried about them being distracted by phones & friends and not bring able to properly pay attention. They both understood why the road thing was important though because I'd spent every school run saying "please stop talking for a minute while I pull out of this junction... I need to really concentrate" 🙄... We all drive automatics as they're much easier. It frees up brain power to concentrate on traffic & directions and not which gear you're in.
So it's a case of slowly figuring out how your DD is affected - what she struggles with, how daily life affects her & also what she's good at. Then she has the knowledge to tell people, especially teachers, "I'm dyslexic.... I'm finding this hard, but I will try to find another way to it... one that suits my particular way of thinking". I found that some teachers were great with dyslexic children & others had NO understanding at all.
This does mean that as others have said you will have to push for help/extra time etc. I wrote SO many emails & had so many meetings to ensure mine got what they needed, especially if they are quiet & well-behaved and just puts their head down & try their best, because schools have so many things to deal with & they can get overlooked if you don't speak up for them.
Sorry it's a long post. I'm really passionate about dyslexic children getting the help they need. I was at school in the 80s, at a very academic public school & no-one knew about it then. I was really great at "talking" my lessons & I know that I had a good level of intelligence/knowledge, but when it came to exams I just couldn't do them & then got labelled as lazy & problematic which made me feel like a failure & I just ended up living up to that and being a difficult pupil.