It really depends on the person. There isn't some universal rule. I know the feeling though. It's kind of like you feel that you are lying by not saying anything. I think you'll know when you can't take it anymore. My suggestion is try to wait for your girlfriend and after that, rather than tell everyone, just say you're lesbian if it comes up. Don't let it be on your mind every second, that will drive you nuts.
Why is it so important to scream it out to the world? You're always gonna feel some sort of rejection from people.
Yea, I've never felt the need to scream out to the world I love women, but then, I don't hide in closets either.
Sounds like you are screaming it to the world right now. Better step out before you start twitching or other side affects happen