Flattering a flat butt

Once upon a time i had a cute little butt, it was never big but if i did wear something tight it looked nice. I was a little over weight at the time but not by much. Ever since i lost a bunch of weight i have NO ASS.. it actually is super flat and the sides where my hips connect there’s a dent on both sides. Not cellulite but kinda like i lost the muscle there. I have gained back most of my weight since becoming pregnant, in my face, back in my legs & arms but my butt is still flat as it was when i lost it. I’m looking for dresses for my shower & have no idea what kind of dress would best suit and flatter my body!! Any advice on that would be nice.