I hear ya! Disney misses the boat on certain sizes, and size 12 is one of them. They seem to be saying that kids who wear size 12 wouldn't be interested in characters, yet what they fail to realize is that tall, long torsoed or larger children could wear size 12 at ages 7 or 8, and that is a prime market for Disney characters! That whole size range is totally lost, as they pretty much stop at size 10, and Ladies or Men's XS is still too large as they are made for adult bodies. It is very frustrating!
My very long torsoed 8 year old wears size 12, and I had to stop buying Disney bathing suits a couple of years ago, as the 10s were not a good fit. Adult Disney bathing suits are made larger, but kids are a smaller cut, as mentioned above.
We scored a size 12 Minnie Mouse dress at a Disney outlet in Ohio the other day, and my DD is thrilled, as she is going to wear it on our
Disney cruise in the summer. But besides that, they don't really do size 12, and Ladies XS is still a bit too large for her.
She used to wear exclusively Gymboree, but they too have shrunk sizes, and last year's size 12, was smaller than the previous year's size 10, so we promptly returned that! We have been having great luck with Old Navy, as they go to size 16 with some clothes, as well has have half/plus sizes.
Costco also sells Speedo bathing suits, and I think they go to size 14?
Good luck, Tiger