I was willing to give up swimming or the sun. Even in High school, I was already a D cup. I just couldn't wrap my head around or ever get used to wearing a cotton t-shirt when swimming or even just sitting at the beach. I started wearing ladies polyester tanks which weren't much better. Then when tankini tops became popular, my problem was solved. I wore solid black blouson tops for a while. After my girls were too large for the minimal support in regular ladies swimsuits, I now were bra sized tops with a full built in bra. Elomi has some terrific tops that work well for me.
It's 2021! Nobody really cares who wears what. If you're comfortable and you aren't breaking any laws, Just wear what fits! If you can fill the cups of a ladies swim top, you should at least consider the fact that it's probably your best choice for comfort and modesty.