Lots of dress styles will look amazing on you. A nice high waist definition in a dress will work to make your waist look slimmer.
Since you don’t have a determined waistline, you’ll need a dress that draws a waist for you, jumpsuits will look good as well. High necklines work well on you, sweetheart necklines and scooped necklines that show off your fabulous collarbones and shoulders.