wear a tight top, and tuck it into a pair of high-waisted jeans or shorts. you'll look like a pinup model.
Nice.
A peplum top or a dress with a peplum will show off your small waist but conceal the stomach. You could also wear any longer top that is full enough so that it can be cinched in at the waist with a belt and forms a flare or flounce effect over the stomach. Both good solutions!! : }