Shapewear
Shape wear is a lifesaver many times, I never go without one under my dresses or pencil skirts.
Not only do they give you a slimmer look they also help your posture.
And sometimes depending on the fabric of the dress or skirt, it helps it “fall” nicer over your curves, and to top it off, they hide pantie lines.
There are many different kinds of shape wear, try them on and I´m sure you´ll find one that works perfectly for you.