Thanks for the helpful info, Shiny! The idea about moving the button was a good one. But I checked it, and there are actually two buttons. The one button is right up next to the buttonhole for the other button, so I can't move the button without getting too close to the other buttonhole. Darn quality construction! If they would have just made the skirt more cheaply, I could have gotten by with the shortcut. :^)
I checked the retailer's website (Asos), and they do still appear to have the next size up in stock, so I sent them an e-mail. I had actually ordered both this size and the size up, but there was a mess-up and they sent me a completely different article of clothing instead of the larger skirt. Of course, this would have to happen with an overseas retailer.
I can't believe how small the clothes are! I ordered what was called a US size 1 and 2 online, and the US size 1 (which says size 0 in the skirt itself) is actually too snug in the waist. I haven't had that happen in YEARS. So they are definitely a retailer I am going to continue to watch. :^)