I've found that the people on this board are so different from most message boards. The people here are caring people. Yes, it is a passion for pets that leads people here. But you will also find an enveloping sense of compassion and caring from the members here.
It does sound like you are seeing some improvements. Small improvements can lead to bigger ones.
I don't know your vet, but I can say, I would most certainly want a second opinion before making the ultimate decision in your case. Vets want to be able to fix things and it must be frustrating when they can't. It seems that there is so little known and understood about vestibular issues. It is great when things clear up, but so puzzling when symptoms linger.
for Mandy walking into her appointment. This is a journey to take a day-at-a-time. And, when dealing with a geriatric dog, each and every day is a gift and a treasure.