Hi Sarah,
Thank you for sending your question to us here at the Disney Parks Moms Panel. You are going to have a magical time with your family and create memories that will last a lifetime!
In terms of Height Requirements, they are in place for safety reasons, and Cast Members will strictly enforce these requirements. Personally, I wouldn't want to put my daughter on an attraction if she wasn't quite tall enough, safety should definitely come first. We had many tears when my daughter realized she still wasn't tall enough for Rock 'n' Roller Coaster Starring Aerosmith, but on our next visit, she was finally able to ride and was so excited!
If your daughter isn't tall enough, I would recommend using
Rider Switch. When you arrive at the attraction, ask the Cast Member if Rider Switch is available, and if it is, one adult (or several if you wish) will wait with the child while the rest of your party enjoys the attraction. When they are finished, the next group will be allowed to board the attraction without waiting in the queue. This is the best way for everyone to enjoy the attraction while keeping an eye on your daughter. While you wait, you are able to enjoy other attractions or experiences around the Theme Park to keep the little one occupied.
I hope that helps, Sarah. Please let us know if you have any other questions while planning your Walt Disney World Resort Vacation, we are always happy to help.
Stephanie