Update: I brought CJ to another vet that my vet recommended (she's far more experienced in separation anxiety than CJ's regular vet), and she doesn't think CJ has SA either. She told me that he just thinks of me as his mom, and he loves me very much. He misses me when I'm gone, but that is normal when a cat has an attachment to his human. She said it's perfectly healthy, though, and to enjoy the love he shows me, because it's not very common in cats to that degree. Haha