First off, please don't apologize! Cats' digestive issues are notoriously difficult to diagnose and solve. Sometimes they get solved even without being fully diagnosed. (That's what happened with Edwina... I'm glad she's doing well but I'd really love to know what to avoid in the future!) It's just awful when a cat barfs and you have no idea how to resolve it. Lots of us have gone through this and I'm sorry you're going through it, too.
Most important, I'm glad Meow Meow really is vomiting less. You said she's less energetic. Do you think you might be able to feed her a little more, with some extra water in the food? Or maybe she's already up to her full ration again? Are you still feeding her the treats (Bursts, I think they were?) that seemed to help calm her stomach when it gurgled?
The baby food and Sheba are fairly simple foods so I could definitely understand if Meow Meow's doing better eating just those. If she was eating food before that contained (just as examples) carrageenan or agar-agar or potato, that would mean she's stopped eating an ingredient that causes problems for some cats... As I said, we've had quick results from eliminating ingredients like those from our cats' diet. You never know. Sometimes luck plays a big role! I remember when I told our vet that Ireland stopped coughing for years (literally five years!) just because we switched kitty litter brands. Yes, she was still diagnosed with asthma but that kitty litter kept her doing well for a long, long time. And it was simple luck that made me switch the litter.
