In the first place, you had a very nice feminine face to start with, a lot of sisters would envy you.
Passing shouldn't be the problem, I think the problem is that you look too much to other people, what would they think, what if they clock you and so on.
Don't give attention to that, just be a girl, if you think, do i pass? you will be clocked, than things will be overdone and exaggerate.
If you are just a girl, nobody would ever think about you're not.
Hey, you're not expect to play a girl, you are a girl, just be yourself and everything will be fine, you'll see.
Happy newyear pretty.