Mine was 3mm x 4mm x 9mm when it took out 90% of my hearing in my right ear. Four months later 100% of my hearing was gone. 6 months of Watch and Wait and the tumor had grown 20%.
I had the same balance issues, lurching from side to side like I was on a boat. I couldn't walk a straight line from my front door to my mailbox.
I had mild tinnitus and dry eyes at night. Both started at about the same time as the balance problem.
After researching my options I selected Gamma Knife as my treatment of choice. It's been two years since GK and I'm satisfied with my recovery. Balance is back to at least 95%, tinnitus is minimal, almost imperceptible. I still have the dry eyes and take drops at night and I'm still deaf in the right ear (no hope for that, I guess).
GK might or might not be right for you. You have to do your research and make your own decision based on all your factors. With a small tumor like yours, GK is very accurate. Another alternative is Cyber Knife, smaller repeated doses of radiation.
This may seem pessimistic but with an 80% loss of hearing it's unlikely that any hearing in that ear will remain no matter what treatment you get.
Welcome to the club that nobody wants to be a member of. You'll get lots of support and good information here.