Hi Bianca!
I'm so excited to hear that you're planning a fun-filled vacation! Walt Disney World is a vacation destination for ALL ages! We've traveled with little ones, and have even traveled with a two-and-a-half year old and a 7 week old! Yes, we did! Enjoyed every magical moment of it!
Most of the attractions do not have a height requirement. There are a handful of more 'thrilling' experiences that do. In many cases your daughter will be tall enough for most of those. Here's a list of attractions with a height requirement so you can determine which ones your daughter might not be able to ride.
Keep in mind that these are only the attractions on property that have height requirements, all the other experiences she'll be good-to-go! Magic Kingdom:
Big Thunder Mountain Railroad
Splash Mountain
Space Mountain
Stitch's Great Escape
Tomorrowland Indy Speedway (will need to ride with an adult so they can operate gas pedal and help steer)
The Barnstormer
Seven Dwarfs Mine Train (once opened)
Epcot:
Soarin'
Mission: Space
Test Track
Disney's Hollywood Studios:
Tower of Terror
Rock 'n' Roller Coaster
Star Tours
Disney's Animal Kingdom:
Expedition Everest
Dinosaur
Primeval Whirl
Kali River Rapids
At almost 5, there's a good number of these that she'll be able to experience, and just a few that she won't.
Expedition Everest, for example has a 44" inch height requirement. You can view each attraction's height requirement on their information page. That information, as well as other handy facts is on the right-hand side of the page.
Have a magical vacation!
Amanda