The Prozac I use for Czarina is a topical, I smear it on the inside of her earlobe. It also comes in pill and a liquid form I believe. Perhaps that's something you can put in her food. The only thing is, it takes up to 3 weeks to even begin running through their system to show change. That's just an option though, it may or may not be something you want to do. I just thought it might be something to help her come out of her shell a bit. You could always talk to your vet about it.
There are only two rules at my house: House rule #1. Cats rule. House rule #2. See rule #1.