Well, you guys are pretty young and in the unique position (more than likely) of being one of the few 'couples' out of your groups of friends. Typically, at your age, it is more common to go to dances with groups of friends and meet your boyfriend / girlfriend there rather than go together (at least that was the case when I was that age - but that was ages ago!)
Maybe think about it this way .... the more she dances with other guys ... and still remains your special friend .... the more confidence you'll continue to build.
Plus the more you're friends, or become friends, with some of these other guys, the more security you'll have as well.