I've begun exploring my identity as genderfluid and it's still very new to me, but recently I've begun dressing and acting like a male when it feels right. I was in class yesterday and needed to use the bathroom, but was terrified to do so because I had no idea which one to use. The building luckily isn't far from the LGBT center, which has a single-user restroom, but I started freaking out about what I'm supposed to do when I don't have access to one.
I don't pass perfectly because I am very large-chested and my binder doesn't get me entirely flat, though a bigger shirt helps. I'm sure it's been posted on these forums before but I can't seem to find it, and searching for it online didn't help me either.

I would really appreciate any help or suggestions anyone could offer me! Thanks so much!