Chloe, the model for this photo shoot is 5'4", usually wears a Small in everything, and was modeling a size small jacket. She was wearing a baselayer but could have easily fit a down sweater or thick fleece under the Helium jacket. I would say this particular jacket fits fairly true to size. It is longer and does taper a bit around the upper waist, so I could understand it not fitting everyone equally well. Hoping others can chime in here too.