NWT Haute Hippie Grey Striped Mini Dress

Brand new, my sister thought I might like this and I do... but it doesn't quite fit me. Size medium, fits on the much larger side, tags attached, adjustable straps. Mannequin is a size 6. Approximate measurements (laid flat): Pit to pit 18" Waist 19" Length 33" (as is, straps are adjustable)