Hi @Blackkitty25 and welcome to the forum.
It's a worrying time waiting for test results. The pits actually! There's nothing for it but to grit our teeth, distract ourselves, take some deep breaths and try not to cross any bridges until we come to them.
The causes of breast cancer are mostly unknown. My mother was diagnosed at the same age as I was, and my sister died from it at 47. Last week I learned I had a CHEK2 gene mutation that highly predisposed me to developing BC, as well a bunch of other cancers. Sucks, but forewarned is forearmed. It sounds like you're in a similar boat and it was wise of you to go for a mammogram at 45. With a family history like yours, early and extra surveillance is a good idea.
At your age there may be an issue with breast density. It makes mammograms hard to read as the dense tissue looks the same as cancers. Try not to stress too much about the length of time and discussion during your mammogram. It sounds like they were being cautious and thorough. When we submit to testing we have to be prepared for the consequences. The treatment of BC in this country is world leading. If you do have something it sounds like you might be onto it early. Which is a good thing indeed. Whatever it is, you're in good hands.
Your GP may just want to talk to you about your elevated risk and what your surveillance regimen should be from now on. There are other risk factors for breast cancer such as alcohol, obesity, and lack of exercise. One in eight women in Australia will be diagnosed with BC; it's extraordinarily common.
So deep breaths, hang in there, and come back here whenever you want for a worry, a vent or a cry. We've all been there, we get it. Do let us know what happens. Best of luck. K xox