The best way to know your size is by measuring it yourself. Here are a few guidelines:
Bust: Measure across the fullest part of the bust and across the shoulder blades
Waist: Measure around the natural waistline, which is the narrowest part of your torso
Hips: Measure at the widest part
We also have a full-size chart on every product page. Do refer to the chart before you make your purchase. The size guide is available here https://adibafashion.com/pages/size-guide