Sarah, just chiming in with everyone else to go down one size for the skirt. I did the same.
Also, there are a lot of items that come in both petite and regular sizes but don't show up when you just look at the petite dept. for the online NAS. I found lots of neat stuff under women's apparel ~ when you click on a particular item, you can see if it's also offered in petite. Not sure if you already saw that, so just wanted to mention it ~ I went straight to the petite section myself, was a little disappointed at the selection, then found lots of petite goodies the other way.