I never really went looking for a dress that would be suitable for the heat and location, I picked a dress I like regardless of all that, prob not very sensible but thats me, lol!
If you type in destination wedding dress into google it brings up things that would be worth a look if you havent doen so already - maggie sottero has some lovely destination dresses, might be worthwhile trawling the designers websites and then trying to find stockist close by.
Try not to worry, I'm sure you'll find your perfect dress soon, you've gone a while atleast so try not to rush it, just enjoy trying on all the fab wedding dresses in the shops