Hey Pippy, and I am not sure where you are but in QLD breast screen are only able to report on findings that they believe are cancer. Private clinics however report on changes and other stuff. I am not sure of the reason. In Cairns where I am if you have any symptoms you are not able to self refer to breast screen but need to go to a doctor and get a referral to a private clinic? It's a bit weird as they are the same place in the middle, but with different offices/entrances. It's all a bit of bureaucracy. I think go with the second follow up tests, the earlier anything detected the better, also if it is nothing it will give you peace of mind, rather than wait two years.
hugs
Paula xx