My heart really truly breaks for you. Trust me - there is *no* right time to let them go - meaning, it never "feels right" to let them go - at least it never does for me, bc I never, ever want to let them go
.
But I think it's very important to be both mindful (intelligent, logical, w/ reason and facts) and heartful (with love and peace and compassion) when we make decisions for these most precious vulnerable innocent precious ones who we have for such a short time
! If time is short - if death is inevitable - if pain is almost constant (or similar) - if quality of life is becoming something you can question.....then.....you may want to start thinking about making that ultimate compassionate decision.
I know it's excruciating to consider -- but like you said, if it's a possibility that something could happen at the vet's - when you're not there...? I mean, if the situation is truly that fragile - I don't know; if it were me, I don't know if I'd want to risk my baby having to pass away alone like that...ya know?
So sorry you're facing such a tough time
. Hugs.