Linus, I say go for the men's room unless it's a small facility, and they watch your every move! However, you already brought it up to them. I wouldn't have. That sucks. I've used both rooms. Depends where I'm at and who's around. Many times than not however, I find I should just stick with the guys.
Here is an article where a 7 yr. old trans boy is denied the use of the boys restroom.
http://www.ajc.com/news/georgia-scho...e-1180991.html
Just goes to show how ignorant people are, even when it comes to children.