I think you have indeed found that perfect balance! Congrats! It sounds like they are all loved and give you joy. What more could you ask? And what more could they ask?
When I had parrots (which I successfully rehomed when going through a nasty divorce) I wrote them into my will, to be given to a specific parrot sanctuary along with donations to the sanctuary. I knew they would outlive me even under the best of circumstances.
I'm a nurse, and I'm also the daughter of a man who donated his kidneys and liver upon his death, *and* the partner of a man who was on the liver transplant list for awhile. I have done a lot of research and seen a lot of amazing things. What you were told when you got your kidney-- things have changed and improved since then, and will change even more before you reach age 65. ALL of us should count each day as the blessing it is, but also be hopeful that your original prognosis may not be correct, either.