When do you know it’s time?

My pup is 21 years old, and the sweetest girl. She still has a full appetite and drinks water plenty. She still seems to moderately enjoy things that she used to, but is a bit sleepier.

She has been diagnosed with CKD and has shown some recent challenges with laying down seeming hard (sitting down first and then sorta falling over to lay down). She also is deaf and occasionally has accidents inside the house - but I think this is because we put her in a diaper when we go out and we are okay if she pottied in it.

She used to twirl before she got her food and I think she has stopped because her hips might be hurting her a bit.

I just don’t know what to do. I worry that my judgement is clouded by all my love for her.