So I got Cats and Dogs, plus My First Pet Stuff.
Which screwed up my game big time, it just wouldn’t load. Ugh.
So I made a backup, and did the factory reset. Game is now fine.
I decided that I wanted to start over completely, like I’d just bought the game and expansions etc, without any of the previous saves. So, my previous games don’t exist in this version, and I’ll be starting afresh with a new family.