A lot of people come into the vintage shop I work at, and complain about being the wrong size for vintage clothing. Truthfully it is more difficult to find vintage larger than a 10, but it is completely possible and honestly, with the right outfit, can be more of a knockout than any little model can hope to be. One turnoff with plus sized clothes is how they hang on a hanger, which is why we have so many great dresses still in the shop that look amazing on a figure but lacklustre on a rack. One reason I love the 1940's and 1950s is because it flatters my figure more than any era, from 20s to modern. I am very high waisted, as are the styles from those times, and while I admire other periods of fashion, I have come to accept that they just don't fit correctly. The same body consciousness should be applied to everyone, and when it is more difficult as a voluptuous girl to find just what she needs, when you know exactly what styles fit best, you can look fabulous whenever you walk out your front door. One measurement often overlooked is the bodice length (Shoulder to waist) but is very important to know. If you have a dress that fits you ideally measure the bodice for reference.
Today I came across a fabulous shop with great plus sized clothing modeled just beautifully. cheesecakevintage specializes in 30s to 60s clothing, and I have a feeling these dresses will go fast.
So while it may be more difficult to find a dress in just the right size, they are out there, and they are fabulous.