Cats can hide their pain so well, that you won't realize there is a problem until it is too late. It sounds like your cat is giving many clues that something is wrong.
As for being PTS, that is your choice, not the vets. You are the cat's guardian, do what is best for the cat, not you.
Cat maid to:
Puddles, female Himalayan (16 yrs)
Jasper, male Ragdoll ?? (approx 9 yrs)
Sweet Pea, female silver tabby DSH (approx 7 yrs)
Rose semi feral, a cpietra rescue, female tabby (approx 6 yrs)
Snowball RIP (1991-2005)
In a cat's eye, all things belong to cats.-English Proverb
“While we are free to choose our actions, we are not free to choose the consequences of our actions.” Stephen R. Covey