Sewing/Altering question: Fabric and advice

Hi, everyone! I have just started getting together my wardrobe, and I've hit a tiny snag. Any advice would be appreciated.



One thing I've received thus far is a beautiful Bodyline striped corset skirt that I want to build a Steampunk outfit around. (It's this one in a brown color scheme.) My problem is the corset portion is too tight for my waist. Ideally, I'd like to find the fabrics used (or as close of a match as possible) and add a panel or two to the corset so it fits my waist.

So here are my main questions:

~Is it possible to find the fabrics used by Bodyline to make the skirt in the first place? (I would simply buy another skirt and cannibalize it for fabric, but the color I own doesn't appear on the site).

~If it's not possible to find the exact fabric, any tips for finding/using fabric that would be close?

~Any general tips on how to go about altering the corset piece?

Thanks, everyone!

ETA: Thanks everyone who has replied so far! I've gotten some good ideas, and I'll definitely check into all of them to see what would work best!