First up, H&M

Heather: Dress: 2, Top: XS, Jeans: 27
Breanne: Dress: 4, Top: S, Jeans: 27
Elie: Dress: 6, Top: 8, Jeans: 8
Catie: Dress: 10, Top: M, Jeans: 14

H&M uses European sizing, so they tend to run small. This was pretty clear with Heather, who wore a larger size here than in most stores. However, Catie actually went down a dress size from most other stores. Basically, we're off to a bizarre start.