Hi Michelle,
Fear not, I am sure that you will still be able to secure some great dining reservations for your first trip to Walt Disney World in September.
I would definitely recommend that you firstly try for some
character meals.
Some of our favourite character meals include:-
Ohana's Best Friends Breakfast with Lilo & Stitch at Disney's Polynesian Resort
Chef Mickey's at Disney's Contemporary Resort
Donald's Safari Breakfast at Tusker House in Disney's Animal Kingdom
Some other fun non-character meals which my 7-year-old son enjoys are:-
Whispering Canyon Cafe at Disney's Wilderness Lodge Resort
Ohana's at Disney's Polynesian Resort
Teppan Edo in the Japan Pavilion at Epcot
Les Chefs de France in the France Pavilion at Epcot
I hope that this has given you a starting point and would recommend trying to make reservations for off-peak times if you are struggling to find availability.
You can search for availability and make your advanced dining reservations on the Walt Disney World website
HERE.
Wishing you and your family a magical trip!