Not to condone their behavior, but it's really hard for family sometimes. Its been over five years and my family still uses the wrong name and pronouns. I have quit talking to them, but if you want to preserve what you have with them, try not to get too overtly angry. Your dad will probably be harder to win over than your brother, but pet persistence may do the trick. Give them a hard time to show this is important to you, but keep it lighthearted. If your brother says he will call you his brother if you grow a dick ask him if you can call him sister when you chop his off