It is immensely satisfying to give in to a brief urge to dress like a boy and discover that I just don't pass as one very easily any more. I can see every single little flaw in my feminine presentation all too well, but a half-assed attempt to go the other way really highlights how far I've come. I'd have to go get something to bind with, wrap it tight enough to impair breathing, and go buy some new clothes, as everything I own now codes for “girl”.
Also, I’ve heard plenty of anecdotes from transitioning transsexuals that once they’re at the point you’re at, dressing as a male actually makes the passing work even BETTER. Probably because the contrast between clothing and form overrides peoples’ tendencies to seek out and notice defects.