Here is the size chart for selecting the Watery Calder Gecko wetsuit for women. The measurements are taken with the suit laid flat and unstretched. The wetsuit will naturally give way with use and in water, adapting to the body while swimming. Therefore, choose the size closest to your measurements.
If you find yourself between two sizes, choose the one where most of your measurements align. Generally, the most important measurements are chest and height (ankle to shoulder).
A wetsuit should not fit too loosely. If you notice many air pockets or "bags" around the suit, it is too large for you.