The top for this suit is great - i'm pretty small up top so it's rare that i find a suit that doesn't gap. however, the bottoms run so small. for reference, i'm a size 0 in dresses and 2/4 in pants. i ordered the xs and s to start, both were too small. with high hopes that i could keep this adorable suit (and well made otherwise!), i ordered a size m bottom. they were still small. sadly, i'm giving up and returning. 
only order this suit if you're super, super tiny on the bottom.