Cola,
Both my AN size and symptoms are identical to yours, and I had VNG testing several months ago. The results of the test showed that my brain is adjusting, now only accepting balance information from my AN side at a 50% rate, but 100% from the good side. That was considered very positive, and is leading to a gradual reduction in the amount of dizziness and vertigo. I understand vertigo happens when the brain gets conflicting balance information, and gets confused. But if it adjusts to know good versus bad information, vertigo is reduced. So, I think the VNG is really sort of like a stauts report.
Jeff