I think it is beautiful and very flattering. Definitely yes on the belt - I feel like it draws your eye up a little bit and provides a nice balance to the full bottom. And of course gives you a great shape! Love the sweetheart neckline as well.
When I started planning a destination wedding I was a little surprised that so many brides wear what would not be considered a typical "beach" dress - but I totally 100% think you should wear whatever you want! There are lots of brides on here with full dresses! Personally, I worry about getting hot but my wedding is also in June and I sweat like it is my job