I use the underworks 997. I have a bigger chest (I used to be a 36F). It won't make your chest completely flat but it does help flatten, and I feel it filled in the gap between my chest, and where my chest ended. My experiences with the underworks tri-top was pretty negative. My chest wasn't "firm" so if I went "down and out" my chest would sort of stick out of the bottom and I never really felt secure. It also rolled in the back in a weird place (plus there was a gap in the front between my skin and the binder.
There are some other things you can do to help conceal a chest unrelated to binding. Wearing patterns, layering, and some other things that I can't think of right now do help. Also, if it's possible increasing muscle mass in your arms and shoulders will make your chest appear smaller.