Great news your gorgeous boy is doing better and things are improving for him. Like other posters, I am a strong advocate of quality over quantity and sometimes dogs will amaze you with their resilience with the right treatment just when you think things are bleak for them.
A few years back, when I adopted Tournie, a beautiful black lab senior boy who I found in a pound a month shy of his 10th birthday in terrible condition. He was very overweight and arthritic, terrible ear infection and eye problems. I adopted him with a view to tend to all his health issues and make him as comfortable as possible for the best qualify of life for his remaining time. Not only did he respond positively to the treatment for his arthritis (cartrophen injections, jointguard powder and fish oil tablets and weight loss with progressively increased amounts of daily exercise) and treatment for his other health issues, he far exceeded the time I thought he would have, living to a ripe old age of 15 yrs 7mths old in pretty good health until around the last week of his life and I was so grateful that he got to live such a long life considering the condition I found him in.
Hope Rocky continues to do well and and sending lots of best wishes and positive thoughts his way for the longest quality of life for him. It can be difficult dealing with the aging of our beloved seniors who are very special but you are doing the very best you can for your beloved boy and he knows he is very loved. to you both.