Where would be a good place to get a dress for an 8th grade formal?

My style, kind of vintage, girlie, very fun, but elegant. it has to be appropriate for my school, 8th grade, not very strict rules on length of dress, doesn't need straps, and i prefer strapless.i don't like long dresses that much at all. and i like for the bottom of the skirt to poof out and the bottom begin under the bust.I woul also want it to match convers. So if you could find some websites and/or pictures,that would be great! ps: i love pink