I had our dog Boomer put to sleep on Tuesday.Did we do the right thing?

We had our 14 year old lhasa put to sleep and I have been asking myself if I should have waited. He could no longer walk or hold in his bodily functions but he was still alert and his appetite was great. The vet said that we were doing the right thing but I feel like I let him down. I miss him so much and our 14 year old son who grew up with boomer is heartbroken. I just feel unsure.Has anyone else experienced this?