Nice to meet you! (: I wish you much hatzlacha on your journey, and it’s really amazing that you’ve already taken tzniut on yourself - it’s definitely not one of the easier things to do.
For a while I wore a t-shirt and shorts, but now I wear a swim-dress. It’s basically a dress made out of swimsuit material (you could also wear a swim-top and a swim-skirt). I got mine from Undercover SwimWear, and so far I’ve had a lovely experience. It doesn’t hinder your movement and it looks nice, too. If you’re thinking of buying one, I saw that they have one of their dresses on sale now for $38 instead of the usual $70 (oy, vey). Here’s the link to their website: http://www.undercoverwaterwear.com/ladies-swimwear/swim-dresses.html
And in case you don’t find anything you like there, here’s a link to a website with listings of other modest swimware companies! http://www.modestclothes.com/jewish/modest-jewish-swimwear.html
Again, much hatzlacha! Don’t hesitate to ask if any other random questions pop up. (: