Should I come out? It shouldn't be that hard, but I still feel like it's a secret

A little less than a month ago I've been completely certain that I am bisexual.
It makes me feel like I know myself better.

The thing is even though I'm bisexual (and at all times have a male celebrity crush) I usually would probably seek out same sex relations.
So I'll probably just come out when I have a girlfriend in university, I live in a small rural place, all of us are cousins.

But, I have a gay cousin who came out to me when I said I was questioning, a close friend and my brother are transgender.
I want to tell them because I want my brother and friend to know that while I don't have first hand experience I can understand from lgbt sites at least enough to empathise, I want them to know that if I misgender them it's because I don't want to out them.
For example my mom uses my friend's female name and while I want to correct my mom it's not my business to out him, and sometimes I call my brother her and I don't want him to think I just dismissed what he told me, he's just not out to anyone except me.

I also want to tell my friend I love one of the pride buttons on his bag, I want one of those buttons, but I don't know if I'd have the guts to wear one.