Well, I don't really know your body type or anything, so that makes it difficult. My first advice is to bind to where breathing ability is not restricted; bind too tight and you might not be able to bind at all due to injury, fluid buildup in the lungs, etc. Binding safely is the first rule, always.
My first question for you, then, is if you're within a normal weight range for your height. If not, working out can really bring down chest size—I've lost 30 lbs and though I haven't measured or worn a bra in 5+ months, I can tell you I've dropped at least 1-2 letters and a good few cup sizes. I wasn't gigantic in the chest area pre-weight loss, but a C or D for sure. So yeah, weight loss is a big helper. If you are just unlucky in the breasts size department and perfectly fit, feel free to ignore this tip.
Also maybe if you posted a picture of yourself, from at least the waist and up, it might help give us some ideas on how to present with a more masculine silhouette/figure.