Swimwear?

Maybe I have too many criteria, but I’m finding it very hard to find swimwear for my July 2018 gal. I’d like coverage so I have less skin to cover with sunscreen. The problem is she is ~25 lbs but over 36”. I haven’t measured her recently but maybe 38”. Prob not any taller. I ordered 3T one pieces from Carter’s based on height and the legs were SO loose on her.

Where should I look? Realistically, she’s 18-24 mo on the bottom and 2-3T on top. I’m okay with a 2 piece set but worry a tankini in 24 mo will be a belly shirt and bother her when it rides up..

Looking for suggestions on where I can buy separates or any other help. Thanks!