Black cap sleeve fitted dress with big bow on back

ADORABLE LBD - Black cap sleeve fitted dress with strap across back shoulders and big bow right above butt on back. It has a Matte leather look & it is so flattering on! No issues at all Brand is Mad rag labeled as a small but it was SUPER tight on me (like barely got into it) and I wear a small / medium depending on brand. I would say it best fits an XS. See measurements P54