Sorry I'm so late with this post, best wishes goes out to Beau, and you for being a great cat-mom!

Fluffy, our senior is also going through pretty much the same problem, and let me tell you, a month after his sub-q's started, he is back to his same ole self!
He even has started to put a few ounces back on (we are working up to a full pound!) Hopefully you will notice a quick turn a round in Beau, from what I have been told, they can live for many years this way

All fingers & paws are crossed over here for you! Get well Beau!