It is possible for seizure activity to not show an an EEG even it the seizures are actually epileptic. Sometimes they come from somewhere too deep in the brain to register on the EEG. I had a 4-day EEG done in the hospital a few years ago, and I pressed the button whenever I was feeling a seizure. Sometimes they tech would sound confused and be like, "Are you still feeling it now?" and I'd say, "Yes" (I have simple partial seizures, so I'm still conscious during them), and the tech would be like, "okay..." And then anyway, the last day, my doctor came in to tell me the findings, and she said that they only caught a few of the seizures on the EEG, so I asked her why and she said that sometimes they're too deep in the brain. But they were able to tell that they came from my frontal lobe and were able to prescribe me a third med and now my seizures are controlled a lot better.
So it's possible that your daughter's seizures are too deep in the brain and she may need an EEG that lasts longer than a half hour for them to be able to catch one. As I said for me, I was on an EEG 24 hours a day for 4 days, and they only caught a fraction of the ones I was feeling.
It's good that she is seeing a neurologist next week. Maybe ask if she could have an extended EEG. Or sometimes I've heard of neurologists suspecting pseudoseizures but they put the person on an anti-seizure med to see if it helps. If it does, there's a good chance that they're actual seizures.
Good luck. Keep us updated.