I have yet to figure out the sizing for them. It just varies so much, depending on what you order. Some things run SO small (PJ Pals -- snug-fitting) -- others run very big (Disney logo shorts -- ordered a size to fit my DD(2) for next spring but they actually fit my DS (6). As far as adult clothes, I still can't figure out what to order. I can never tell what size to order for myself -- some things I wear one size and then the next item, that size will be too small for me. Go figure!
One thing to keep in mind -- they will no longer allow you to return things from the catalog or online at the Disney Stores. That's such a bummer for me! That way, if I thought there would be a problem, I'd just order both sizes (if there was free shipping) and return the one that didn't fit. I can't do that anymore! Oh well, maybe that will save me money -- I won't buy as much this way!
Good luck! I have always been impressed with the quality of the clothes. I've never had a problem with things shrinking -- even the PJ Pals, even though they are snug-fitting, they didn't seem to shrink too much, or if they did they stretched back out.