At Holy She we are here to help so if you have a question about your size please send an email to firstname.lastname@example.org and we will come back to you asap.
The kids swimwear has a tight fit. Thanks to the very stretchy material it will still be growing with the child for a while. If you are sticking to the rule "child's height equals size", you will be choosing the right size for regular and slim kids. Please also consider, that swim suit fabric (lycra) does get wider when wet.