You could order a adult plate and split the meal with her. The portions I've found are so large that I can't eat a standard size meal, even at the counter services. Last year I ordered the seafood platter at Millies, and it was so huge, that it could have easily fed 3 people, and could barely eat less than a 1/4 of what was ordered. Something to think about.
They don't have too ~ have her order from the kids menu, now at character meals you'll have to pay the adult price which is a bummer especially when your "Disney Adult" doesn't eat much, but I figure I'll be ok with it for DS once he's 10 ~ for the past year + he's been out eating me! We just might not do them as often.
We had no trouble getting kids meals at counter service, but at full service they charged the $5.