Vintage Cache sequin halter dress - runs small

Super cool sequined, vintage, halter cocktail dress by Cache, size 12, but runs small; might be about size 8?; see measurements. Black and white sequins in a swirl pattern; lined. Has a horizontal, pleated hem...I really think is silk chiffon, although the tag does not say. Satin trim & tie around the neck. Side zipper & hook. Approx 18" pit-to-pit; approx 16" across waist; approx 17" across hips. 32" from scoop neck to end of hem. EUC. This dress is ready to party!