Sweetie, there will always be people who try to make you feel uncomfortable in your own skin. Never give anyone that power! You are in the process of a personal metamorphosis, one which takes courage that most of us will never know. Continue your transformation with the grace, dignity, and pride that you have shown and surround yourself with love.
Also, you handled the situation with her with controlled dignity - you go, girl! She might have been born a female, but you're the real lady here!