Just to make this more clear on it, the Official Disney Princesses, according to the Disney Princess franchise, as it stands (because yes I've looked into it):
-Moana
-Mulan
-Merida (the only non-Disney Animation Studios)
-Pocahantas
-Cinderella
-Aurora
-Snow White
-Rapunzel
-Tiana
-Belle
-Jasmine
-Ariel (despite being non-human for most of the film, she's made human at the end)
-Raya (most recently added)
Qualifications for princesses require great acts of heroism (Mulan, Moana, and I assume Raya?), being royalty (Rapunzel, Jasmine, Aurora, Merida, Pocahantas kind of, Ariel), or being married/romantically linked into royalty (Belle, Tiana, Snow White, Cinderella, also Aurora and Ariel). They also have to be primarily human, hence no Nala or Miriam. They also have to have been created in a theatrical release, and in the first film, not a sequel. They also have to have been popular enough to market, but not so popular that they spawn their own franchise. Frozen was so big it spawned its own franchise, so Elsa and Anna don't qualify.
Esmeralda was technically a Disney Princess for awhile, but didn't sell enough so she dropped out. They were planning on pushing Tinkerbell, but made her the head of the Disney fairies franchise instead and replaced her with Tiana. They also planned on making Jane a princess as well, but they don't have the rights to Tarzan anymore, so that's that. Apparently Disney also wanted to use Giselle, but since she was partially live action, there are rights involved with merchandise.
Just so everyone knows what's technically a Disney Princess.
Disney princesses who probably could qualify but don't:
-Kidagakesh (Atlantis The Lost Empire)
-Vanillipe von Schweetz (Wreck-It Ralph)
-Elsa (Frozen)
-Anna (Frozen)
-Nala (Lion King)
-Elonwy (Black Cauldron)
-Tiger Lilly (Peter Pan)
-Miriam (Robin Hood)
-Esmerelda (Hunchback of Notre Dame)
-Megara (Hercules)
-Giselle (Enchanted)
-Princess Atta (A Bug's Life)