I am 5'5" normally about 120lb, but i'm about 145lb now at 9 months prego. i purchased the small. i can't resist buying retailer clothes, even though they might not fit me currently! however, because this shirt is drapey, it actually fits over my baby bump now and it will be perfect as a nursing shirt and then regular shirt later. it is so soft and great quality. will be cute dressed up for work or down with jeans!