Hi Nadia,
Welcome to the group and sorry we had to meet this way. You will find lots of interesting facts opinions and stories as well as tons of support on this forum...so first off, official welcome!!
Second, try and stay calm and focused....these types of growths...grow very slowly so you have time to sort out all the information.....
Third....Surely your HMO has other doctors on the plan....so call another superviosr and ask, whom within a tri state area is available for this....the best option..,,my opinion only...is a doctor that specializes in both radiation treatments and surgery, that way you get a really non biased opinion as far as treatment....now, watch and wait is a common option although I am unsure about the time period for follow up MRI, but I believe typical is 3to 6 months for follow up....but, I am sure it can be longer...a lot depends upon your age also....many times these do not continue to grow...so watch and wait is a good option....
Read as much on these threads as you can absorb and research...talk to highest supervisor at insurance company and keep being persistant.....they will eventually comply.
Good luck and keep us posted and remember we are all with you.
Ceeceek