How to know when it’s time to say goodbye to your furbaby?

Just found out on Saturday after multiple visits to the vet that my baby has mammary cancer(it’s a mass in her tummy area) that has spread to her lymph nodes and possibly her lung as well as necrosis of the skin and an enlarged kidney
She walks okay she struggles with balance and is a bit wobbly she constantly pees everywhere (I know it’s not her fault ) and rarely poops
She drinks a lot more water but eats no problem she basically like her normal self but not at the same time her tail wags when people come in and seems excited even for treats
She currently on meds to help with the pain but I feel like there not working aswell as before she’ll sleep for a couple hours then get up and pant and pace
This morning she could barely even get up she struggled sorry for my rambling it’s been a rough week
So how did y’all know when it was time?