Hello Tatiana,
I think you should get second and third opinions from neurosurgeons with a lot of experience treating Acoustic Neuromas. Your tumor is clearly growing and there are risks involved with waiting. The larger the tumor is when you finally get treated, the more likely you are to lose hearing and experience other symptoms, such as balance problems. Right now, you have the choice of being treated with radiation or surgery. If your tumor grows to 3 cm or more, you will lose the option of being treated with radiation and you will be required to have surgery. Larger tumors poses a greater risk of hearing loss and facial nerve damage.
With a small AN such as yours is right now, you can treat the tumor and still preserve your hearing. I have a 2.6 cm tumor and underwent Cyberknife six months ago and still have good hearing. There are some people out there with ANs smaller than yours who lost there hearing very suddenly. Others have larger tumors and still have maintained their hearing. The bottom line: waiting does not mean you will preserve hearing. While the tumor is growing, there is no way to predict how the nerves will respond -- whether you will lose hearing or start to experience other symptoms. The best way to ensure hearing preservation and prevent other symptoms from developing is to stop the growth of the tumor by treating it. And the smaller the tumor at the time of treatment, the better off you are. If it is absolutely certain that your tumor is growing, I am not sure there is any benefit in waiting.
At the very very least, I would have your next MRI in three months or six months, definitely not a full year. But again, I think you should see other doctors and seriously consider treating the tumor now, while it is still small. Don't be shy about contacting expert doctors anywhere in the country by email. I found neurosurgeons are quite willing to discuss ANs without necessarily having a formal appointment/consultation.
Sincerely,
Francesco