I’m so sorry about Jazz. That’s rough.
I also understand your predicament about being very busy and not having much time to bond either — and if doesn’t work out, you have to deal with two separate bunnies. Not easy. Do you have a rabbit rescue near you? Some rescues will help you with bonding. For example, SaveABunny.org, helped one of our members with his tough time bonding his two and the rescue provided a service to bond for them. I’m not sure what the cost was, but I’m bettin’ it was worth it.
As far as a cat, I also don’t think that would be a good idea — Rabbits and cats have different needs and different body languages. Though there are cats that will get along with bunnies, many times cats will just stay away from them (or like ours, has to be closely supervised). Some bunnies will bully a cat or a cat will rough play or accidentally scratch a bunny. The bacteria that gets caught in a cats nail can cause some nasty infections in a rabbit if they scratch them — nasty abscess caution. Young cats will be much more playful and I would caution against that with a bunny.
So, my vote is for another bunny — take Hoyla bunny dating when you are able to have any time off, and if they offer a service to help them bond, I would go for it.
Good Luck and keep us updated.