Add the cutest sherpa to your closet! This is a button Sherpa vs the snap Sherpa our snap Sherpa has sold out with this one not far behind.
 
Fits true to size. I am 120 lbs and 5'6 and sized up to a medium only becuase I have long arms. 
If you have long arms I recommend sizing up. If you have a regular build true to size would fit. My mom has a bigger chest area than me and shorter arms, she got sized in a small when modelling. There is a lot of room in the chest, arm length is different on this one due to the material of its build. 
Photo market reference picture, she is tall with long arms and got a medium.