If this is a true story, I think she probably went in the sort of very upscale, snotty, New York department store where the sales help has the attitude that you are lucky they are letting you spend outrageous amounts of money on their shit. I don't know of any large store that wouldn't have 14 and 16 a-plenty.

And clothing sizes in this country are BS. They don't fit anyone. I've spent a lot of my life in jeans and a t-shirt because t-shirts always fit, and you can always find a few pairs of jeans that fit, somehow.