Hi Charlie55
Your anxiety is very understandable, I think most people feel it. For me, I try to put it in a little box and think about anything but. I have the mentality that whatever is or isn’t there, I can’t change the outcome whether I worry myself sick or put it in a box, so I choose to do the latter.
I too, like you had no warning whatsoever. I was called back from a routine 3 yearly mammogram. The mammogram showed my breast was clear but I had 2 swollen lymph nodes. Even a thorough examination at my call back appointment suggested no lumps even in my armpit where the mammogram picked up the swollen nodes. Was told they had probably swollen because I had had a recent flu jab.
Unfortunately another mammogram, tomogram, ultrasound and 5 biopsies gave me the dreaded news of breast cancer plus 7 cancerous lymph nodes found during my op. This was November 2024.
Since then, an operation on December 18th to remove the cancer and all of my axilla nodes, (I had 12 in total) (also opted for a breast reduction while they were there) 6 months of chemo, 15 daily radiotherapy sessions, now on Letrezole, Abemaciclib, Calcium + vitD and about to start Zoledronic acid infusions in the new year.
My first annual mammogram is due tomorrow, Christmas Eve of all days
but don’t know how confident I am in the mammogram as it didn’t pick anything up in my breast last time, apparently I have dense breasts 
I spoke to my Oncologist the other day and asked would I now be considered to be in remission and she said as I had had every treatment offered, then yes she would consider me to be in remission.
I know it can be a really worrying time, but try and put it out of your mind if you can, as I said earlier, worrying won’t change the outcome anyway.
Hope all goes well for you, try and enjoy Christmas and best wishes for the new year 
Diane