Youswim is a small swimwear brand based in the UK. Their one-size system is meant to fit seven different sizes!
Promising review: “This swimsuit is AMAZING. As someone who wears a 36D, I am just shocked at the support that this swimsuit gives me up top without any padding or under wire. You can move and nothing falls out. When you first pull it out, you’ll wonder how the top is going to even cover a nipple, but then magic happens. The bottoms are high waisted and great! Overall, fantastic investment and the customer service is great! Don’t overthink this decision, just but the swimsuit!!!” —Samantha J.
Get it from Youswim for $139 (available in one size and eight colors).
Source: https://www.buzzfeed.com/alifacc/high-waisted-bathing-suits-youll-want-asap