Sounds familiar (except the quitting smoking part). When I hit my late 40s it seemed that all of my weight maintaining tricks quit working. Not sure exactly how to proceed, but I”m muddling thru, as I refuse to be the FAT grandma!
I believe I inherited my dad’s genes in the metabolism department, and if all goes according to plan, I don’t think I will gain much more weight from here on out, with almost exactly one year to the big Four-Oh-My-God!! :)