Welcome!
If your school system does not have a gifted mandate, and therefore won't test her, you could start from the pediatrician, by asking for a referral for a neuropsych, but that usually requires some kind of problem area, and it doesn't sound like she is presenting with difficulties, other than not feeling like she fits in with age-mates. You can also pay out-of-pocket for an eval with a private school, clinical, or neuro psych. Or you can go to a university clinic/training program, where it will probably cost less, but testing will probably be conducted by a psych intern. Where you go, what you have done, and how much it costs depend largely on what your purpose is in testing.
Are you comfortable with giving us a little more information about what you hope to achieve by testing? In-school advocacy? Applying to a specialized program/school or private school? Qualifying for a GT supplementary program (e.g., CTY, TIP, EPGY)?
