Seems like pretty good news all around after reading this.
2. Stable tiny bilateral pulmonary nodules without significant FDG uptake,
though possibly below PET resolution.
3. No evident recurrence/metastasis.
Pulmonary nodes without significant FDG uptake & no evidence of recurrence. Don't look for problems that aren't there. Enjoy the good times now and deal with any issues that "may" arise when they arise.
I spent too much of my time worrying about possible recurrance that I spent several years of my life not enjoying my life and I certainly wish I had done differently now. You can perhaps help your Mum by letting her enjoy the "now" instead of letting her worry about the future. I get it that you are scared, but keep that inside and just be mindful that they are your fears.
If the doctor is not worried, then I don't see that you have a lot to worry about until something bites you in the bum, which it may never do.