There's no such thing as standard sizes any more (no matter what stores claim) and different styles in the same store can fit different.bif you are a size A at one store it doesn't mean you take size A in a different store. Stores have size guides on their websites and will list body measurements in chart form to help you choose your correct size. You will need chest, waist and hip measurement. weight is irrelevant, size is obtained by body girth measurements. 

If you've bought the wrong size check the stores return and exchange policy. If shopping in person always try on before you buy. If buying online always be sure that you can exchange merchandise that doesn't fit.

The company is European so it is very possible for sizes to vary.

maybe you can go and exchange it