I third Torrid.
I am about a 2X now and I also find the Disney 2X small (at least for t-shirts).
The only "complaints" that I have about Torrid is that the clothing can be a little "young" for me...so the dresses are a little shorter than I would normally wear (I'm 5'4" so the dresses aren't too short on me, but if I were taller, I'm thinking I might need to size up). Also, you have to watch out about their "distressed" look. I guess I'm too old to appreciate my top looking moth-eaten. (I just bought a Jurassic Park shirt that has tiny holes all over it on purpose!). For theme park wear, I'm not really concerned about those things, though.
I do have to say that a lot of their dresses have pockets! It is so amazing! lol
ETA: You can usually find some kind of sale to help bring the prices down...and I always go through Ebates.