small sized girl wearing for party

I am looking for a long formal dress,size 11 or 13.My granddaughter was asked to a military ball next month and it is a
Formal event. She wants a dress appropriate for her age(15) as well as the event. Anyone have a dress for sale, please pm me with photos. Thanks in advance. She is running short on time as the ball is March 2. small sized girl wearing for party