In most seizures, a cause isn't identified. A normal CT scan doesn't mean she does or doesn't have seizures. Also, EEGs can be read by doctors differently. One doctor may see some subtle changes, that another doesn't. Witnessed accounts are very helpful, as are any sensations she feels before, during, and after. Depending on the part of the brain being involved, any combination of symptoms can occur. It's really hard to rule out seizures vs pseudoseizures in all of hers, simply because of the video EEG not picking up electrical changes during that one.
Maybe make a list of questions for her, and have her write some for her next doctor appointment.