Finding a bathing suit can be daunting. There you are all your "flaws" out, trying to find the most flattering cuts, what enhances your bum or bust, what covered that scar you're not fond of, and all the other concerns we conjure up for ourselves to focus on and feel worse.
I say fuck it. Pick something that you like, you feel good in, and keeps your breasts in! Enjoy the actual beach. Enjoy the water and the sand. Play volleyball or soccer. Practice yoga and do your crunches. Go surf.
Do what you need to create your vacation. Enjoy the moment and don't worry about your insecurities. You weren't born to be perfect. You were born to be real.