Black pencil skirt, size S but fits like a M

I bought this skirt thinking I would grow into it. I didn’t. The skirt has a small slit in the front, 2 pockets on the front, 4 buttons down the front. white stitching detailing. Has a bit of stretch to it. The faint white line is just from it sitting on the hanger, I will wash it before I ship it out.