Most people weigh more than they'd like, and those who don't stress about a few extra pounds generally think they're too thin. Only about 10 percent of adult women are comfortable with their current body weight. Often, this means women are either ignoring weight gain by cramming themselves into clothes that are too small because the size on the label is somehow reassuring, or they're using one of a number of camouflage techniques -- usually jackets, big shirts, sweaters, dark colors and other layering methods to trick others into thinking the extra bulk is really just fabric.
Choosing the right size garment, whatever your size happens to be today, is an important element of looking good in clothes. Unless you're swaddled in spandex, and maybe even then, insisting on a size 6 when you should be wearing an 8 or larger isn't doing yourself any favors. It could make you look even bigger due to the bulkiness. Covering up the problem with outerwear designed to drape and conceal probably isn't fooling anybody, either.
Forget the skinny model ideal and own your body. Models are super thin to make the clothes look good. Dress to make you look good. Take measurements of your bust, waist and hips and buy clothes designed to fit the real you, or find a good tailor if you do have a hard-to-shop-for body. Your clothes will last and look better longer that way, too.