Where can I find a dress like this one?

The long back skirt isn’t as important as the basic structure of the dress. I have a large cup and small band size. This is pretty much what I’m looking for. I’m not sure if she’s being held up by my the dress or some kind of bustier underneath?

If anyone can help me find something like this? If not how would I describe it to a dress/corset maker I would be most grateful. Thanks 😊