Go find a girlfriend who doesn't expect you to talk to the elders.
Lotta fish in the sea. Most have problems. There are worse problems then cult membership, but there are a lot of problems that are far smaller. Get one with one of those problems.
She can't be that hot!
Nothing you say will matter. You can't reason with her, because she is not interested in truth. She is interested in protecting her sacred ground.
Think of it this way. You have some thought that if true, would be simply to difficult to bear. Let's say you are really gay deep down. Now as you stand, I could show you a picture of you doing the nasty with say Charles Taze Russel. Are you going to give a damn about my picture? No! You are to scared to consider the idea that you might be gay. You will likely get hostile, and want to punch me for suggesting such a thing.
Your gf wants/needs to believe that the jw is God's organization. Only she truly knows why that is. Maybe she was raised in it. Maybe she had a bad experience and now is overcompensating by seeking the security of a group that has it all figured out. She doesn't have to question anymore. She doesn't have to doubt her conscience. She simply has to obey.
You need to figure out as well as you can WHY she needs to believe this garbage. You also need to figure out ways to encourage her own personal growth such that she will trust her own conscience enough to question the org. Right now if something doesn't make sense to her, she assumes she is to dumb to understand the amazingly perfect org.
You cannot attack the org. To do so, violates her sacred ground, and makes you a threat. If you have done this, stop. You can ask questions. But showing her some thing you found on the internet will likely make you an ex boyfriend.
Read the previously mentioned book by Steven Hassan, or his newer book, Releasing the Bonds. Hang around here. We get a guy like you about once a week.
Or just go get a gf who isn't in a cult.