I know I haven't been on this forum long, but I think we could be a little more sensitive towards this guys issue. Now, I agree, the obscenities gotta go bro. You can talk about your situation in a more sensible manner that adheres to the rules of the forum. But I'm not replying to rat on you about that.
Listen, I really do think you like this girl. And if she asked to you to get married, that does say something about how she feels about you. But don't confuse your emotions with what your heart tells you. The physical feelings you might get when you're with this girl, don't act upon them. They can be misleading. Give yourselves both a chance to live. I know the desire to be with this girl for the rest of your life is strong and sounds very appealing, and I believe that emotion to be normal... even at your age. It makes us human. Heck, I was with a girl for 9 months with I was 15 and I was talking about marriage. I loved this girl so much, I wanted to spend every waking second with her. It drove me crazy when I didn't get to see her. I finally realized later on down the road, sometime after we broke up, that our emotions can drive us to the point to where we become so blinded we can't even see whats good for ourselves.
Now, the Bible says in Chorithians that you should put your spouse before yourself. I agree with that totally. But it is only talking about after you have tied the knot. I don't know if you believe in God, but God does want us to love ourselves and take care of ourselves (i know i'm referencing the drugs again, but I still hope you're trying to quit). Praying helps too. Try talking to God and see if He gives you an answer, or at least a different path to travel.
All in all, I can't tell you what you should or shouldn't do about this girl. Just know, don't rush into this decision based off just your feelings for this one person. There is a difference between Love and Emotion. Love is everlasting, but Emotions tend to fade. Its all apart of growing up.
Good luck with everything.