Help Needed, any military wives ?

Hello all, 
I've been married for 4 years to a handsome military man. But I've never been to the ball..I try to stay away from the military world (if you are a military wife you know the drama 😉). This year my husband bought tickets and asked me if I wanted to go, I don't really want to go but since he already bought the tickets I'm assuming he wants us to go. 
Long story short, where do I buy the dresses? Like is there any good LEGIT (nothing from those horrible websites that takes forever to come and will probably end up in "why you should never shop online" article) websites?? Also, we live in Japan right now and the Ball is in December 😒 I need proper elegant dresses, ships very fast ! 
Thanks in advance. 
PS : I'm super nervous and I have no idea what to expect, share your experiences please! 
❤️❤️