Mine grew fast, but others grow slow. You can find out by getting another MRI in six months. Mine grew from 2.7cm to 3.5cm in 10 months. It was removed 99.5% with very few problems. While I would NEVER recommend waiting so long for one my size, the moral of the story is the 2nd MRI told me mine was fast growing and that information helped me finally decide.
I see you focusing on the negative, as I did. That is part of why I took too long. Focus on the positive. You probably do have some time, and more options than I did (eg, wait/watch, Gamma Knife, Cyberknife, etc). Get several opinions from experienced teams. If you don't like the Canada system, traveling is an option. I traveled from NY to House Clinic in California, and got an excellent result. You can send MRI to them for a free phone consult, which you can get very quickly.
We all wish we had a guarantee but we had to accept there is none. But you can absolutely give yourself a great chance by getting several opinions from experienced teams. Let us know how it goes.