Pink and purple striped button-down shirt dress, size medium (but fits small)

From Dresslily (https://www.dresslily.com/double-pockets-striped-print-shirt-product8415024.html). Can be worn as a dress or long shirt. Size medium, but fits more like that weird uncharted region between medium and small). Nothing wrong with it: just doesn’t fit me, and I missed the return-by date. Worn once to try on, new with tags attached. Currently priced at $30, I paid $22 on sale, selling for $20.