Hi, Ultra--
We found our neuropsych through a children's hospital. By then we suspected autism, so we chose one who'd seen lots and lots of autistic kids. We were not fussy about whether they'd seen gifted kids; we felt then and still feel that the disability was driving the major issues we saw rather than the giftedness. In your case, I'd want to make sure they've seen lots of girls with ADHD and/or AS and are able to recognize those even in gifted girls--because girls are under-diagnosed.
We went through the hospital's autism diagnostic program, but they were fully equipped to come out with some other diagnosis too. I'd definitely choose a neuropsych rather than a regular psych; they are more finely tuned. Ours happened to work with a developmental pediatrician as a team, screening for lots of physical and developmental things all at once, which worked fine for us. Insurance covered the evaluation, which was long (6+ hours).
If you can, start keeping a journal of behaviors that seem unusual or troubling. That gives you evidence, and keeps your mind from going blank at a key moment in the evaluation process.
On the therapy side: it can be hard to find a cognitive-behavior therapist who works with kids. Here's a "finder" as a place to start:
http://nacbt.org/searchfortherapists.aspDeeDee
p.s. about insurance: ask the neuropsych's office how people usually fund evaluations. There may be options other than your private health insurance available in your area, especially since you suspect there could be a developmental issue.
