And yes, I have trouble finding clothes that fit too.
I'm 5'3", very short-waisted and long-legged. Slim from the rib cage down, (VERY) top-heavy with broad shoulders. I wear a 2 to 6 depending on the brand, or size zero for the brands that do "vanity sizing". I've been very happy with the recent trend to low-rise waistbands since on me they're not low, but just right. Now that high-rise waists are coming back, I might be doomed to wearing my pants just under the bust line again (sigh).
I'm the right height for petites, but they're always cut for girls with lots of curves, so they sag in the bottom, hips and thighs. Make me look like I'm wearing clown pants. Clown pants that are too short.
Since the shops usually only buy one size 2 in whatever styles they carry, I can never find anything in my size, especially not on sale. That said, I can shop in the children's department and usually luck in with a size 12 or 14 girls.
Jackets are the bane of my existence. Because of the giant bust and broad shoulders, I usually have to buy an 8, 10 or 12, and then have it cut down to fit me from the rib cage down. I've taken to buying stretchy things wherever possible, and HATE blouses made from woven cloth. Yuck.
Honestly, there's no such thing as the "average" size woman. We're ALL hard-to-fit in our different ways.