@New Trader and riddle, Thanks a lot for the information and @mancini Thanks for the link.

@Gorikopoi,
Yeah, I kinda feel like I'm moving fast too but just look at my situation. I am not really the hot type of guy any girl would like to date. Even when I was in Nepal, I didn't have a girlfriend. This girl I'm dating right now is my first girlfriend. She is really beautiful or at least for me. Next thing is about my American dream. I've met people who have stayed in US for 12-14 years and still can't get a green card. I think I have this opportunity that will never come to me again to settle in US. I like your idea of waiting. But, what if she meets another guy by then and gets the feeling that she can get a more hot or rich guy than me?

Its been 8 months. I am not taking her advantage or using her to get my dreams come true. As of now, she likes me. I don't know what will happen tomorrow. I haven't talked to her about Green Card but she kinda knows that I can get a green card and settle in US if she gets married to me.
I want to plan it in a way that when I graduate school, I want to have a legal work permit in my hand.
Thanks.