Could you selectively come out to more people, people that you know that don't know your brother? When I finally came out to my parents (at age 21) I felt like I was out to the world. There are still some people that don't know I'm bi/pan, but that is because they don't need to know.

I personally believe that your sexual orientation isn't anyone's business unless they want to date/sleep with you. Straight people don't have to come out, after all; no one sees being straight as a key part of their identity. I don't think being non-heterosexual should be a key part of someone's identity either. That is not to say that you haven't encountered significant struggles due to your sexuality; of course you have! I'm just saying that you shouldn't let it define you.