Thank you so much for replying, everyone! It has been about 3 weeks since I posted my question; I'm sorry I haven't checked unitl now.
Bubba uses his cart only outside. In the house, he scoots around or sits on blankets or in a chair. He does seem to be getting some movement back to his legs
. When I change his diaper, he decides to punish me by pooping on the floor... yuck. But, I think this is a good thing as he obviously can control his bowels now. I still leave the diaper on him, because when he needs to go potty, he simply can't wait. He can wag his tail now (I'm so happy for that) and yesterday when he was sitting in the floor, I noticed that he was up on his knees - I was VERY encouraged by this! I don't expect anything miraculous, but hopefully he will recover enough that he won't need to use the diapers any longer.
Again, thanks so much for advice and words of kindness. This has been nearly as hard on my as it has been on Bubba.
This is a picture of my Bubba.