No the girl doesn't have a skirt in the catalog.
When I first started out I panic when I changed into a dress. I thought I lost the skirt and than I figured out she didn't have one.
The female character wears a gray skirt that doesn't actually exist. Once you put on a dress, skirt, pants or shorts, the gray skirt is gone. However, if you're wearing a dress and then change into a shirt, you're wearing the gray skirt again. It's like magic... LOL
Another cool thing is if you're wearing a dress and then you put on a skirt, pants or shorts, you'll be wearing an undershirt that, again, doesn't otherwise exist.
To use the skirt you just have to put on a dress and then only put a top on, so I mean it's not like you can't use them anymore after changing. Same with the shirt if you just put on bottoms.