Hi, looks like you have some pluses and minuses to deal with. I didn't follow did they think she does or does not have ADHD?
It seems like ADHD and the relatively low processing speed supports ADHD. I would a) focus on supporting her ADHD (there are many techniques, like small notepad for remembering things, clocks in every room time timers for tracking time, writing down all assignments), b) try to find something she is very interested in (e.g. beast academy from AOPS or Hopscotch (programming) or Scratch (programming) or minecraft modding or math olympiad, and work on that at home. ADHD CAN focus on things they are strongly interested in and she needs something positive to support her positive abilities. Good luck!
