Does anyone know where to get grade 8 grad dresses?

Ok, I'm 5'7 and I would like a kind of shorter dress with thin straps. As well, I don't have much of a chest, so do you know any dresses without any large cups?? I like dresses with a bit of poofy-ness in the bottom and any colour is fine... but please keep in mind that I cannot fit into anything breasty... thank you :)