How to make look fuller in a dress?

Pretty dress! The shirring on the bust alone will make your s look fuller. In my experience, wearing a good strapless bra will give you nice and fullness because they push you up and in a little. My favorite ones are from Gap Body, although I'm sure you can find some decent ones elsewhere as well. I think Victoria's Secret also makes good push-up plunge bras with a halter option, which would suit your dress nicely.