On the vision angle, a ped opthamologist, for the most part, is not going to find the things a behavioral optometrist will - it's not the same type of evaluation (there are rather few opthamologists in covd.org; most are optometrists, long story). My DD8 was checked by a ped opthamologist a couple years ago and all was good; that same month when we took her for IQ testing, the testers said she might have a vision issue. Took her to an optometrist (this was about two months after seeing the opthamologist), and lo and behold she had an eye tracking problem. It's fixed now thanks to vision therapy. Of course, that doesn't address a lot of the adhd symptoms but I just thought I'd throw that out there, just as a little FYI.
Besides the second opinion, the other, probably less desirable option is to try the medication for a limited time to see if it helps. But I were in your shoes I'd probably feel better if I felt sure about the diagnosis first. Is there something specific from the diagnostic criteria that she's missing, or does your 90% figure just come from your not being 100% sure? What kind of doctor was it?
Good luck, I hope you get this mystery figured out soon!
