Petite does not mean skinny in the fashion industry- petite sizing recognizes the differences in proportion on women who are under 5'4 tall- regular circumferences at the shoulders, bust, waist and hips, but a shorter distance between all of these markers.

Looking at the statistics, this should include most of us being that the average height of women in Canada is 5'3 and a bit. World wide, average height for women is about the same if you do not include Scandinavian countries where women tower over the rest of the world at about 5'6 on average. 

Visit a specialty store if  1.) You measure less the 5'4   2.) You find that your blazers and dress shirts bunch up around the waist in the front and back (caused by a short waist/long legs)   3.) You find the crotch of your pants is no where near your crotch (caused by a long waist/short legs)

Pictured above is Judy, built to represent standard proportions. The cross markings are of my own 5'1 frame at the bust, waist and hips. Although Judy and I are a similar girth, I am petite.