We know my 7th gr (12yo) girl has ADHD & ODD.
Your dd sounds just like mine except, mine hasn't been diagnosed with ADD. My daughter was diagnosed with unspecified learning disabitilties. That means she pretty much has disabiltities in all area, poor memory, reading, writing and math comprehension. She has great conversation skills though and is a social butterfly. She is also artisisric. Dd will never be a great student. It worries me because life can be hard with out a university degree. We encourage her to engage in activities she does well try not to focus on poor grades as long as she is showing that she is working hard. I feel for you and your concerns and I wish I could offer some great advice and easy solutions.
Vision issues do come to mind.
Dyslexia comes to mind, as well as Vision problems. She may be having issues with vision and not even realize it. There are several things that come to mind, such as Executive function issues, Irlin Syndrome, and a couple of others. I would not hazard to guess what it is myself. Could also be a Comornbid, or other disorder, and not ADHD or ODD.
Has the school tested for LD's? They would pick up on Dyslexia, and other issues, but some will require a specialist, such as an Opthamologist.
Is she taking meds? That could also be an issue, depending on which med it is.