Hey Eliana,
You're a beautiful girl so you do both dresses justice. You look great in both. In my opinion, the first dress is more of the beachy tropical feel you're going for. The second dress is beautiful as well, but think about how hot you'd be in it. Either way, I don't think you can go wrong. But follow your gut and pic the dress you absolutely LOVE.
It's ok that your FI just said "it's nice". I mean, what guy is really going to say, "OMG, that dress is absolutely gorgeous"? We all hope that's the response that you get but realistically......lol
I'm sure you'll make the right decision and be gorgeous in either. Tick tock though, gotta make that decision quick.