Honestly this isn't something you should be getting that upset over. You're taking it way too personal especially when you don't know them and they don't know you, let alone even knowing your transgender. They arent calling you "he" becuase you're transgender and are trying to be offensive because they don't even know.
I'm female and I'm not bothered if someone I probably won't party with again calls me he. If after awhile we still continue playing together and become friends, I'll just mention that I'm actually a girl. No big deal.

And if someone wants to correct me when I use the wrong pronoun on someone, go right ahead. Just don't be rude about it. Although I do admit, when a girl says, hey I'm a girl! It can come off as annoying/attention seeking.