Just some observations from our December trip:
Early in the trip, DH saw a shirt he liked but they didn't have the size he wanted on display. He spoke with a CM who very willingly offered to go to the back room and she found what he wanted. This CM told him not to hesitate to do this in any of the stores...we found want we wanted a couple of times this trip by asking CMs to check in back.
I've seen more XXL and XXXL items on display over the last two trips, but those did seem to be more "gender neutral" items, not specifically women's. I also noticed, as others have said, that you really have to look item by item to figure out what size to buy; one family member takes a women's XS but can sometimes wear size S from WDW, depending on the cut.