What are your DD's specific issues?
My Y7 DD was diagnosed in Y3. Her particular issues are spelling and punctuation, writing is very painful (hypermobile fingers), and because she struggles a lot with translating sounds into written letters MFL is a total nightmare.
The best thing we have done is to teach DD to touch type (used English Type Junior which is dyslexia friendly and fun to use) and she now has a laptop for pretty much everything except Maths and PE. It has made an enormous difference to the quantity of work she produces. There is a read-back function so she can listen to what she has written which helps with editing skills - plus spell check etc.
We are planning to try something like Dragon Speak once I've had a chance to speak to the SEN dept and see what they recommend.
DD does not find reading fun, so will not read for pleasure - I buy her audio books instead. We also use kindle so that she can use the dictionary features.
Have also found that she likes graphic novels and scripts - no idea why, but she seems to find reading plays a lot easier than a normal book.
DD also learns things much better if she starts with a synopsis of an entire topic. So, this is what A to Z is going to cover, and then doing the individual bits. If you start at A and work through to Z, half the time she hasn't understood the concept, panic sets in and she learns nothing. Ensuring that the overall concept is firmly understood before adding any detail seems to make a massive difference.
Make sure that if your child is entitled to extra time in exams that they also get this for tests in school. We discovered that DD never moved up levels in Maths in primary because she never got 50/50 in the weekly tests... she always got 48 or 49 because she never finished. However, her working memory and processing speed scores mean that she was fully entitled to 25% extra time.
It's a big learning curve.