Buying my first bikini--help!

(x-post from femalefashionadvice) It's summer and I'm dying of heat without an A/C. All I want is to be able to go to the pool--but I don't own a single swimsuit, and haven't for years. I went looking for bikinis at Old Navy but my breasts seemed to be falling out of even the "large" labelled tops. Where are reasonably-priced places online or in store to find bikini's for larger busted girls? I'm 25, about 5'5", weight 125-130 lbs, 34D/34DD (depending on bra), I'm also sensitive about my thighs so hoping to find bottoms that are more like board shorts than regular bikini bottoms. Thanks for any advice.