Finding another prom date?

About a month ago, I asked my best friend from another school to my senior prom and she said yes. Well tonight, I asked her if she still wants to go since I would be the only person she would know and she said that it would be best if I went with somebody else :( The options that I have now are: Ask my best friend to reconsider, ask a senior, ask a junior, or ask somebody from another school. After doing a lot of thinking, I realized that I have a lot of friends in the senior class, but none that I'm really close to. I have a ton of junior friends as well, a few of which asked me last year to take them to this year's prom. And finally, I could very well get somebody from another school to go with me, but it would be just as awkward for them as it would be for my best friend. What would you do if you were in my shoes? I wanted to ask my best friend out since sophomore year, but now I most likely have to find somebody else.