Welcome to the forum! I believe there's Cinderella's Royal Table, Akershus, and 1900 Park Fare (dinner only). I'm sure someone else will chime in if I missed any.
I think Cinderella, 1900 Park Faire and Akershus are all of them, with the date being so soon 1900 Park Faire or Akershus would be your best bet at getting ADR"s. Cinderella usually is gone soon after the 180 day mark.
They've all been mentioned, just wanted to throw out that the Akershus breakfast is our family favorite for Princess dining. We have had the best experiences there with our almost 4 year old girl.
1900 Park Faire only has Cinderella at dinner time. The other characters are Prince Charming, her step sisters and step mother. If you're looking for multiple princesses this is not a good choice. Definitely work on one of the other two options.
It is true that it is hard to get those ADRs. But I have heard that persistence pays off. It worked for my family we were able to get most of the ADRs we wanted. The hardest to get is Cinderellas royal table. I have been told to try 1 -2 weeks before the trip as well.
Stalk the website and be flexible. Search by meal and search all restaurants. Search many times per day, especially as you get closer to your arrival date. People thin out ADRs in that time and you can often pick up great last minute things.