I do think most of us have to struggle with a version of this, Lyn. We have to learn how to "translate" the look online or in the catalogue or even on the hanger to ourselves, our own unique shapes. And even those who are nominally the same size as the models can be sure the clothes will look different on them than on the model unless they are as tall and thin as the model -- which hardly any of us are.
This works against us, when, like Denise, we're hoping we'll look similar in the clothes. It can work *for* us with certain items. For example, wrap tops and dresses often look awful on the models (in my opinion) but will look a whole heck of a lot better on most customers (except, sadly, for me, but that's another issue!)
This particular dress looks like the cut and style that you frequently wear. The diagonal pattern *might* be slightly broadening...but then again, the pattern might just as easily be minimizing, moving the eye away from "trouble spots." (Not that you have any). I think it will look as good on you as all your fit and flare dresses (assuming the colour works); it will just look different on you than on the larger model.
The problem here is actually not as extreme as the one many shoppers face, because although this model does look larger than you, her overall shape is similar. She has a slim hourglass body type, a bit fuller in the bust (maybe?) than in the hips, which I believe you do, as well? So at least you know the overall impression the dress will give. When a curvy woman has to compare an item to a stick-straight model, it can be really confusing to figure out. Which is why Angie's idea is so great and why YLF is so great!