Welcome to planDisney, Rachelle!
Oh, bother! I'm sorry that you're having trouble making
dining reservations for December 26. This is indeed a very busy time of the year and so it's certainly possible that all the restaurants you've tried making reservations for are fully booked up. However, it's also possible that there are simply no tables big enough for 11 people. If I were you, I would try making two reservations, one for 6 people and one for 5 people. It's often much easier to get dining reservations for smaller groups. On the day of your visit, you can always explain to a Cast Member that you're part of one big group and request to be sat near one another. It's not always possible, but it's worth asking! Cast Members usually try everything within their power to make it a magical experience for the Guests.
If you're not able to make dining reservations at any table service restaurants, there are many quick-service restaurants that serve delicious food. My favorites are
French Market Restaurant in New Orleans Square (which is right next to the
Mint Julip Bar. Did someone say Mickey beignets?!),
Bengal Barbeque in Adventureland (not massive portion sizes, but very tasty), and
Docking Bay 7 Food & Cargo in Star Wars: Galaxy's Edge (I like their Felucian Kefta & Hummus Garden Spread).
I hope that's helpful, Rachelle! Have a great Christmas at The Happiest Place on Earth.
Thanks for stopping by planDisney.
Mike