What does she see me as: boyfriend, backup, friend?

You are just a really comfortable friend at this point. You need to just let things flow naturally with her. Don't push or change anything. Every girl needs that one guy friend to be close to and get the boys side of things from. Let her breath and enjoy the ride and freedom of having a super cool girl friend. If you push the issue, she will back away from you which is the opposite of what you want, no? Also, consider this, some of the best relationships and greatest loves, come from 2 friends that spent a lot of times as friends first and truly knew each other before then ventured into a relationship.