Hmmm, I suppose that again that depends on how an individual would rock being NB. If they're concerned more with passing than looking androgynous, then yeah, broad shoulders are gonna make passing pretty difficult. But if you're trying to look androgynous, you can work with your feminine and masculine qualities to create a hotpot of aesthetic. I know a male crossdresser for instance (identifies as male so I call him that), and he passes really well, despite having broad shoulders, an adam's apple, a strong chin, being 6 foot tall, etc. Mostly because of the makeup, dress sense and general air that he carries himself with. Learning body language tips will help a lot in the long run; when in public, think about the way women and men walk, and try to emulate the walk you want to go for, think about hand gestures when speaking, tone of voice, all of that stuff. When you become conscious of such things, you find them easier to change, and you realise that your form is under your control, like clay waiting to be crafted.
I do have a tendency to ramble, but essentially it's all in your confidence and your social knowledge of how women and men are expected to behave. Once you know what unspoken rules most people follow, you can break them at whim, if you want to. Maybe other people will see that and realise they don't have to perform either. It can be a freeing experience.