Should I buy this AP dress or wait?

[thetinycakes.livejournal.com]

Hi everyone,
I was wanting to ask all of you a question.  I am pretty new to Lolita and want to buy my first name brand dress besides Bodyline.  The one on my wish list is any of the Whimsical Vanilla-Chan dresses, meaning both JSKs and the OP, in any of the colors.  I was wondering which one would be better for me to search out?
But my big question on the matter is that if the Tiered JSK has a bit of shirring in the back would it stretch larger around both the waist  and the bust? The waist being 69cm and the bust being 86cm.
If not I will still try and get one of the others that are at least 4cm larger in both.
Please help me. =(

Here are a few examples from Hello Lace of the back with shirring.
More info on Hello Lace: http://hellolace.net/wardrobe/angelic-pretty/type/jsk/item/331/