You have definitely not "lost the plot" and sound like a lovely, caring person. I slept downstairs on the couch for a couple of years when my wonderful, old, blind and deaf boy (a shepherd mix) could no longer climb the stairs like he used to and he was too heavy for me to carry.
After he passed on Dec. 23rd, 2010, I couldn't imagine getting another dog but then my son showed up on Mother's Day, 2011 with a small terrier mix puppy. Of course I loved him right away and he was my little buddy for the next 14 years. He passed last week due to his poly-cystic kidney disease. Of course, when I say "passed" in both cases, I mean I had to make that dreaded trip to the vet to say goodbye probably a little later than I should have, but it's never easy to make that decision.
Toward the end, he would wait for me to pick him up to carry him up the stairs or over tall door jams. I actually came on Gransnet today to see if there were any posts about grief after losing a furry family member. Right before I had walked upstairs and was tearing up, again, remembering how warm he felt against my heart when I would carry him up so, obviously, this post stood out. 