Well, I think you shouldn't continue to be so "available" to her. Next time she wants to go do something, tell her NICELY "Hey, yeah I would but I have plans, raincheck?"
Distancing yourself from her a little bit can help you to put your feelings into perspective. If she wants to be "just friends" then you need to treat her like a friend. Tell her when you think another girl is pretty, or even attempt to date available girls in your area!
If the girl has feelings for you, they will get stronger the less time she is able to have with you. (i.e. you being too busy to cater to her every need)
I'm not one to play games, I think this girl likes bad boys and that is something she has to work out by herself. You, on the other hand, should remain friends, but keep your options open so you don't feel like you are putting everything into this girl, and therefore making you feel more vulnerable around her.
I personally don't see a point in wasting my time with someone who doesnt want me back. I want to be wanted by the person i want. Get it? It's a mutual "like" thing and its a great way to start out a potential relationship!
I'm not good at beating around the bush or sugar-coating things. My responses are never personal vendetta's on your emotional state. It is what it is, whether you choose to accept it or not. <3