Where do I find a baithing suit in the Winter?

Okay, well, my friend and I are going to the Dells soon (Wi) and I need a baithing suit! I've gone to Target, Walmart, and Kohl's but they have nothing! I am an XS in Juniors, or a 0 or 1. I can't find any appropriate baithing suits for me! They are all string bikinis, skimpy and like tying at the sides, I want a two piece, just nothing risque. (sp?) Any places where I could find baithing suits in my size, in the late winter, early spring? Online shopping is always an option! Thanks so much!