Hi Melissa!
Don't give up on those Character Dining experiences. Even right up to the last minute, you can get lucky with someone's last minute cancellation. Keep checking online and by calling (407) WDW-DINE. A couple of great ones to try and secure would include:
Akershus Royal Banquet Hall for Princess Storybook Dining at Epcot's Norway for lunch time and Donald's Dining Safari at
Tusker House for breakfast or lunch at Animal Kingdom.
There are plenty of great opportunities to meet the most popular Disney Characters around all four parks. Upon arrival at each park, be sure to pick up a Times Guide which will list all character greeting locations and times for the day or week.
Town Square Theater at Magic Kingdom is a great spot to meet Mickey Mouse and many of the Disney Princesses. Over at Epcot, Character Spot in Future World features many of the classic Disney characters including the Mouse himself. Buzz Lightyear is found daily in Magic Kingdom's Tomorrowland as well as over at Hollywood Studios in Pixar Place.
Although there is nowhere to 'meet' Nemo, your daughter will surely enjoy boarding a clam mobile to ride through Nemo's 'Big Blue World' on The Seas with Nemo & Friends attraction in Epcot's Future World. There's also the fantastic Finding Nemo - The Musical over at Disney's Animal Kingdom Park.
I hope these tips help your daughter to experience all the magic you're dreaming of!
If you have additional questions, please don't hesitate to write me back. I'd love to hear from you again!
Wishing you a simply Magical time at Walt Disney World!
Kirsten