I have only felt once that it was definitely the right decision at the right time. That was a dog that was very injured in a two on one dog attack. The last one, I definitely waited too long. It was only a week, but what a horrible thing to put an animal I loved through. The decision is personal, difficult, and many times does not feel right. We do our best and love the next one that purrs or wags into our life.
I just hope you find peace when the time comes to make the decision for your current furry friend.
I had a brother and sister. The brother dominated the sister so much, I had to spit them up. By the end of the first year, I had them from the age of 5 weeks because their mother was killed, she would cower when anyone walked up to her. She had never been hit in her life. She still would show submission, but after she and her brother were split she did gain some confidence. I gave her to a friend and was able to visit with her the remaining 12 years of her life. She was a great dog, I wish I could have kept them both.
I have lost three cats to kidney/bladder problems over the last 26 years and have wondered if the food plays a roll in their problems. So actually, I am on a quest to find the best cat food I can. I was feeding a high protein food, but the local stores have quit carrying it. Off to do more research.