Well um... Thanks for the complement ^////^
Yeah a binder would help definitely, but at the same time it has to be a good kind. I don't know much about the science of binding to decrease breast size, I hear It's supposed to break down the breast tissue a bit, but you want to be careful with anything that breaks down tissue. But yeah, with something to help hide the breasts, most shirts should work provided their not too form fitting. But the skinny jeans I know must be something that's hard. You either wear them and keep the curvy look or sacrifice your style for now in order to avoid them, tough call. I'm not sure, but abstaining from shaving arms, legs, etc might make you look more manly, or cut your hair. However both can be sacrifices, particularly the latter, that can be troublesome. I mean, Leg hair grows back fast but cutting your hair is semi-permanent in that it takes months to regrow.
So for passing I think we are getting down to more subtle things I guess that can help you pass. Mostly avoid crossing your legs and such. You can place an ankle on your other knee or something, but guy's have too much baggage down there to cross their legs well. (I can painlessly double cross mine ^~^) lean forward a bit, hands or elbows on your knees, legs spread a bit, is a fairly manly sitting pose. I guess any way of sitting that allows you to get up fast, and takes up some space, but not too much, is fairly good. Steriotypically men are the protectors,t hey need to be able to get out of that seat fast just incase after all.

In general most guys won't sit all the way back and rest their back on a backrest. In fact they almost avoid it. These are things I used to do before I started questioning myself, things I guess I was trained to copy from other guys. and I've seen my dad and other guys around me, paying some attention to how they move. (Mostly after I started questioning it and thinking of what to avoid doing. I didn't want to seem more manly after all.) Guys also lean forward when walking. Don't expect great posture unless their raised by strict parents, or something else, or they have prior/current military training. I guess exercise instructors and the like too but meh. Also, avoid sucking your gut in. most guys would rather not hide any fat if it meant being less comfortable. Perhaps wear less colorfull clothes? (It sounds like you don't anyway.)
Again these are all what I have seen and my opinions.