HELP! dress help pleaseee?

sooner then later my boyfriends sister is getting married. they are a HUGE family of russians, so as you can imagine, the wedding is going to be huge and quite up key. Most of his family will be coming down from Russia and are all very excited to meet me. my problem: i cant find or figure out a single dress to wear! i live in ontario, so any actual good dress stores are welcomed :) thanx in advance. OR a dress, i want an about knee length dress with little or no cleavage, flowy, shows off small shape that will look cute with some very nice heels aha thank you :)