The good news is you got a lot in your favour. Shes single. You have a repor with her friends. Thats about as good as its going to get.
I was in a similar situation in high school, I did end up asking the girl out, even though I knew she probably had a bf. Just so I could get into her life, crazy huh. Was mad crazy looking for chances though. Getting them alone in a school setting is almost impossible. And doing it infront of their friends just isnt going to work.
So maybe stalk to get that opportunity. Just dont get caught
Your unlikely to get her alone in the limited chances you have left unfortunately if you dont.
The best advice I could give is 2 things.
1, it really wont seem as hard as you thought once youve done it. Youll wonder what all the fuss was about. And a huge weight will be off your shoulders. Just keep reminding yourself of that.
2. Its impossible to follow the advice of bring her down to the level where shes just a girl, we both know that. But you have to bring her down somewhat. Dont put her on a pedostool. Truth is, we both know, even if she did go out with you, relationships where the guy worships the ground the princess walks on, never work out. They dont want an asshole but they want a man - remember that.
So bring her down a little. Shes always going to be your princess - but shes a human. Remember that. Despite the sun shining out of her butt, she could also be the worlds biggest bitch deep down too, and then youd be releived you found out and didnt waste any more time.
Oh, maybe write to her if you cant talk? Seems a bit corny but if you wrote a poem or something it might capture her heart. Also the facebook factor, you could always add her and talk on there..just make it out like your not doing it just cause your too chicken to talk to her. Or you could do the FB thing after a short convo in person, its easier to get all this out online, though it would be better coming from you face to face.
Hope this helps.
All the chips are in your favour. Just make it work. Your running out of time. Youll probably chicken out a few times too, so factor that in! If you only got a couple chances left, dont piss around!