My brother is homophobic (or should I say transphobic? but he doesn't know the diff) and I think he's ashamed of me and makes sure I hardly have any contact with his friends

But he doesn't say anything about it.
My eldest cousin is a jerk and always calls me tomboy in front of my parents. And my parents don't accept me and so it pisses me off when he uses it especially in front of my parents despite me always telling him not to because I feel it's straining my already bad relationship with my parents. So one day, while we were alone and holding his neck in a almost death-like grip, I told him never to use the word in front of my parents or his mom or he'd wish he were dead. I think he got the point because he was sweating like mad and never did it again. I'm way shorter than him btw but he is scared of me when I get angry.
(I'm 21, my bro's 17, and the eldest of my cousins is 12 but he's already 5'7"(his dad's a giant). the rest are 10 below)
5 of my little cousins were questioning me about it. They all basically asked the same thing, "Achi Claire, are you a boy or a girl?"
And I'd ask, "What do you think?"
Then they'd say, "A boy! A girl! I mean boy boy! Girl!" And then they'd shake their heads in confusion.
To one of the older ones I said, "I'm a boy here" *pointing to my head*
She said, "Oh" and never brought it up again.