It is possible that these are underestimates of her ability; cognitive testing at this early age is always a bit of a question mark (though I think it can still be quite informative regarding current needs). If you want a more stable measurement of her ability, that will probably have to wait for another couple of years at least, especially if she does have something in the ADHD category. Many parents find that formal testing results change substantially after treatment (not that I am pushing meds if they are unwarranted; that is a conversation for your health care team).
It sounds to me like the observations and classroom reports are more important, as, on the one hand, challenges with self-regulation beyond what is age-typical, and negative self-concept about writing, and, on the other hand, high performance in classroom academics, suggest that
1) there may be a genuine need or second e in the area of executive function/self-regulation. And you already have a Dx of dysgraphia.
2) her current school placement has been fairly suitable for her.
So yes, you likely should continue looking into her EF and scaffolding for it, but also, don't stress yourself too much about it, since her school situation appears to be pretty good, outside of the writing (which you should have some recommendations for from your evaluator). Smart but Scattered is an excellent starting point. "Putting on the Brakes" is another classic:
https://www.amazon.com/Putting-Brakes-Understanding-Taking-Control/dp/1433811340/ There is also a child-oriented workbook in the same series:
https://www.amazon.com/Putting-Brakes-Activity-Book-Kids/dp/1433804417/
