Hi
Yesterdays and Welcome to the board
I can't tell you when you know you're gay, and I doubt anyone here can. I think you need to really listen to yourself, your feelings. Are you (still) attracted to boys/men, do you feel drawn to them etc. Or do have those feelings for women? If you have a crush on another woman you already know that you're capable of falling in love with girls, so I guess the question you're asking yourself is whether your bisexual or not. As I've written before, listen to yourself, try and figure out what feelings you have for guys.
In my case it was pretty easy, I had never really been in love with a boy, at least not the way I would fall for women. And over the course of time I kinda grew disgusted by the the thought of having sex with a man, whereas I dreamed, fantasized etc about women. Plus, I had always felt very strongly about women, even before I'd realized it was sexual.
As for your second question, I really cannot tell you when to come out. I don't know where you're from, but I knew beforehand that I wouldn't get into trouble for being gay. I had no idea how my mother would react, but I knew that here in Germany gay people are accepted and gay couples have almost the same rights as straight couples. But the reason I came out was solely because I felt suffocated by the straight lifestyle. I needed to talk about my attraction to women, I needed to have my family stop treating me like I was straight, I actually resented others considering me to be straight. In short, I felt like I was living a lie and I wanted people to know that I was gay.
Coming to your third question, I think it comepletely depends on where you're living. Over here being gay is nothing special. Of course there are people who might resent you for your sexual orientation, but overall I think discrimination against gay people is very low in Germany.
There's a great website you might want to check out
www.afterellen.com