I skimmed over the some of the key points here.
It sounds like you don't have any close family (parents, siblings) or friends (who know you well at least) to talk to about this or you wanted to make an entertaining LRC post.
I don't know if I saw this, but consider your age and where you are with your education and career (including graduate school plans) and hers. Granted, change happens. If there's a mismatch that's going to be a strain on developing a relationship. The friends with benefits thing won't go on indefinitely: one of you will want to take thing to another level (marriage), or one of you will get stale (move on) and it will only be more difficult to that. You may need to be the adult in the pair (even if you are younger) and speak up if you see things ahead that she doesn't. You know the situation best.