Did i get a dress that will outshine me?

When I was shopping for dresses, my mindset was that I want a cool stand-out dress. And I got this gorgeous couture gown for sample sale price! It's a super cool dress, but I'm worried the intricate design makes me look shorter and wider, and the dress outshines me.
I'm so anxious these days that I picked the cool dress rather than a dress that really flattered me and makes me shine. I didn't originally want to have a traditional simple looking gown, but now I've changed my mind? I tried on one many traditional looking gowns that looked so lovely, but I denied them because they weren't interesting enough.
Tempted to go back and plead for an exchange? I haven't altered it yet. 6 months until my wedding. How flexible are these places with final sale contracts?Or should I run with the risk and try to pull off the cool looking gown? I'm scared I'll have that "you're not wearing the dress, the dress is wearing you" vibe...