Hey there Anna and welcome to planDisney. Your most sensational, inspirational, celebrational, Muppetational day of the year is two days away! I can not think of a better way to spend my birthday than at the “Place Where Dreams Come True.” Happy Birthday!
I would be very surprised if the theme parks were at capacity anytime in the middle of December. If theme parks reach capacity it usually happens between Christmas and New Year's Day. However, you will need a
Theme Park Ticket with the
Park Hopper Option to be able to park hop from your original
theme park reservation at Magic Kingdom Park to another theme park (EPCOT).
planDisney Pro Tip: When you enter Magic Kingdom Park on your birthday go to City Hall and pick up a "Birthday Button." Wear it proudly all day. You never know what enchanting moments await you. You may also order a
Celebration Cake to be presented at your restaurant for your birthday dinner.
Anna, I hope this information helps you have the most spectacular birthday. Please feel free to
write me back directly if you have any follow-up questions.
Enjoy making many Magical Birthday Memories.
~Jason