what I mean is, take a drawing of charlotte, a screenshot of her standing up straight. Mark the top of her head, then compare the proportions of her height to the width of her skirt.
I did a character with a huge skirt once. I'm 6' tall. So I blew up one of the screenshots so that it was 6" tall in photoshop. It happened that her skirt was the same width as her height. So I knew I had to make my skirt 6' wide. ^_^...
Does that make sense? measure how tall she is compared to how wide her skirt is, then apply that to your height.