Michael Costello x Revolve dress

Bought this dress online & couldn’t return - never worn. Would be beautiful if it fit properly. Runs large - it was too big on me. Size M but fits more like a L. For reference, I’m a size 6 and 5”10. Below are the details from website: PRODUCT DETAILS 95% poly, 5% spandex Made in China Hand wash Partially lined Pull-on styling One shoulder design with asymmetrical back straps Lightly ruched slinky jersey fabric Front cut-out and hem opening