You really can't pay attention to what size the label says. It's really a cruel mind game designed to make women feel bad about themselves. LOL. I have clothes ranging from US sizes 6-12. Even within one store, I may be two different sizes (depending on the cut, the fabric, whether it's a skirt or pants, etc).
I worked part-time in a women's clothing store in graduate school. Our petite cutoff was 5'4, and a lot of women try on regular pants that fit everywhere but were too long, so I'd tell them to try on a size larger in petites, because they'd be the exact same cut in the waist/hips/thighs, and the length would be shorter. The'd freak out and get angry with me because they didn't want to wear a "bigger size." Instead, they'd buy the regulars and then pay extra to have them hemmed, all because of a stupid number on the label.