I started by unpicking the waistband all the way around except for the couple of inches on either side of the zipper. I wanted to avoid having to reset that zipper at all costs. I took in the waistband on the side opposite the zipper so that it would fit snugly. Here's how it looked with the smaller waistband.
I thought I could just add a few small pleats on either side of the existing ones, but the skirt ended up very full in the hips. It was not a good look. So I took out all the small pleats and put it five big box pleats instead. It was tricky to figure out the math on that, but I finally worked it out so that the skirt was the same width as the waistband.
I reattached the waistband the way it was originally sewn on, with the raw edges of the skirt and inner waistband facing matching up and stitched together.
I folded over the outer facing of the waistband and top-stitched it down to finish the skirt.
Now it is nicely fitted and still has that twirly feel. And two pockets! I can't wait until it is warm enough to wear it!
Here's the before-and-after shot. Thanks for reading! -Amy