Shape-wear for birthday dress

So I need help my birthday is September 18 (well thats a Monday and this outfit Is for the week following that Monday) I'm turning 17. And I wanna look really pretty so I'm order this dress and jacket off of fashion nova. But I need help... I'm a thick girl and I have a stomach. And I really just don't want my stomach jiggling while I'm out and walking... I'll put a picture of me below.... But I need help with shape wear.. something to keep my stomach from jiggle. Are there any good place or order off online like to get a garter from?