My mom went through this last year with her Min Pin. He was 17 years old, blind and deaf. My mom didn't feel it was time to let him go yet because he was still eating and pottying regularly. He stayed in the bathroom while my parents worked and each night my mom had to wash the rug because he had urinated on it. That was the way it was for probably close to a year. But my mom didn't mind. She had a few sets of rugs, so while one was washing a clean one was down.
In the summer of 07 my dad asked me to take Kodi to the vet to be PTS and to not tell mom. I flat out refused. I would take him to the vet to be PTS but not without telling mom. I went to mom and told her what dad had said. She began to cry and said she didn't think it was time yet. No problem.
In September of 07 she finally made the decision to let him go. He had become confused and could hardly walk anymore. She had told me she wouldn't be able to be with him while they did it. My niece took her and Kodi to the vet and had the excuse to take the other dog out of the room while they let Kodi go. So my mom went through it all by herself, but she was there for Kodi. He was 17 1/2 years old.

I guess what I'm trying to say in my long babbling post here is that YOU (and only you) will know when it is time. Please do not let anyone tell you to make that decision before you want to. I didn't let my dad take that away from my mom and nobody should do that to you. It sounds like it is not Sasha's time yet. So just enjoy the time you have.