It sounds very encouraging that you've found a private evaluator who is interested in understanding your dd - it will be interesting to hear what he thinks after you have the results of his testing!
FWIW, I have a dd with a seizure disorder and one thing you might want to do before your initial appointment with the ped neurologist is to think back through your dd's developmental history. The neurologist will most likely start before birth and ask a lot of very detailed questions that may seem very odd but all fit together in understanding your child's neurology. It sounds like you haven't suspected seizures, and fwiw we didn't suspect them in our dd until she had the type of seizure that was so obvious you couldn't miss it... but we realized in hindsight, after talking to the neurologist and going through that developmental history, that she had in fact been having seizures for quite some time, we just didn't realize that you don't necessarily lose consciousness or have convulsions with a seizure.
The other warning fwiw, a child may have a seizure disorder and have a perfectly normal sleep-deprived EEG - that initial EEG is just a 45-minute (give or take a few minutes!) look at brain function. Our dd, for instance, doesn't have predictable seizures and they weren't happening constantly, so she's never had one appear during an EEG. It's possible that the neurologist may want to have an MRI also.
Good luck as you move forward,
polarbear
