HELP!!!

I have a rather posh wedding to go to 4 days before my due date and I need a dress! I don't really want to spend a huge amount on something so I am desperately hoping there is a fabulous dress hanging in someones wardrobe that you wore when you were pregnant that you might want to sell. I've been looking on Ebay and can't find anything that takes my fancy.

I am a size 12/medium and would rather something long, not necessarily floor length but not short.

The wedding is November 10.

Can any of you lovey ladies help a fat girl in distress?

P.S I live in Melbourne so if anyone has any suggestions of a maternity shop that has fab frocks I might be tempted to buy new...