I had the exact opposite problem. I did not feel welcome at my undergrad GSA because I was straight identifying at the time .
I volunteer at a local HS near me. The teacher heading the GSA is a friend of mine. This school which is in the town I live in didn't have a GSA before this year. The turn out was pretty amazing. Just as a little background so the OP didn't think I was just blabbing. One thing I noticed is that the students that started the project are all out and comfortable with themselves. but that a good number of the students are simply using it as a social meeting place. Much like Chip said. They had a meeting today and as the opening they wanted to introduce themselves to each other and say whether they are gay or straight. I suggested they NOT do this as it might be too intimidating for people in that "questioning" bucket to admit it. instead I suggested a game called 2 truths and a lie. The idea being that when you introduce yourself, you tell two truths and a lie. It gives each person the opportunity to out themselves if they wish. Or to be obscure about it. While I understand the OPs frustration with GSA being filled with straight identifying people. odds are, they aren't all straight and need that time to come to place where they admit it to themselves first and then out loud to other people. Being in the group and being supportive in a way that might allow one person to come to you and talk to you might allow you to help other people admit it. Just remember to build GSA as a place where people can be themselves. But hang in there... It is one of those places that can foster friendships that can help when you need someone who you can identify with. (and vice versa)...
To be honest your lucky, I've got shit all to do with meeting LGBT anywhere near me. I only know three other LGBT's. :icon_sad: