Cute semiformal dresses?

Ok, my eighth grade formal is on May 8th, and its already April 23!!!!! The date wasn't set til recently, and I'm having problems finding a dress. I am very petite, but can shop in juniors if an extra small or occasionally, a small is available. I've been kinda looking online, and I've looked at: Delias, Charlotte Russe, Forever 21, Alloy, and Wetseal. They all had cute dresses, but not in my size....any suggestions??? The "formal" is really semi formal, and slightly formal or sundresses are appropriate...THANKS!!! will give 10 POints for best answer, and will be sooooo appreciative!!!! Thanks ya'll!