My recomendation, GET THE MAMMOGRAM!! Call your doctor's office, explain what is going on with insurance and they will either help or refer you to someone who will. If all else fails, get with the Komen organization for a mammogram. (I paid for mine for 3 years because my old insurance did not include my breast center in its coverage -- I live in South and it was only $196 for mammo, $96 for doctor visit. I bet you could even make payments). You did not say if anything had changed since your last mammo. All this worry may be for nothing but trust me it is much less expensive treatment if it is caught earlier than later. I know. I did not have mammo for 3 years so my cancer was caught much later so I had to have 2 rounds of chemo and then radiation. Just because you are unable to pay does not mean that you can't get treatment.
Please, please call your doctor and start moving forward NOW. Some of the other ladies on this forum will respond with other ideas also. Good luck and let us hear from you.