I'll second the suggestion of a thorough neuropsych eval - some of what you've said sounds a lot like my HG+ dd who has a challenge with reading (she has difficulty associating sight with sound). It took quite a long time to find out what the challenge was, simply because she was able to compensate thanks to her other high abilities. Unlike your dd she did well in school, but she's a very driven personality who always wants to land on top and approaches almost everything competitively. When tested in school she always "looked" a-ok - because the benchmarks used at school for diagnosing challenges are so low.
I wouldn't go to a neuropsych specifically seeking out a certain type of eval or following a lead on a specific suspicion of what's wrong - I'd seek out a broad eval, let the neuropsych know where your concerns are (again, not the suspected diagnosis but what she struggles with in school, observations such as difficulty with oral reading or refusal to do certain types of schoolwork etc). The neuropsych will conduct a wide spectrum of testing which includes ability vs achievement and will then make recommendations. If there's a speech/language issue present, the neuropsych will likely refer you on to an SLP eval which will include more thorough testing of expressive and receptive language. Or if the neuropsych testing points to a different challenge, you'll likely have follow-up of a different type recommended. The neuropsych eval won't be the end-point of the journey (if there is a challenge), but it will be the place you can (hopefully) get a roadmap that shows you where your dd is starting and where to head next on her journey through understanding/remediating/accommodating/etc.
Best wishes,
polarbear
