I'm with Anna re: the green dress for a day wedding. Plus, you could always make some tweaks (different heels, put your hair up, add some bling-y earrings) to dress it up even more.
Also, I know this isn't as much fun, but unless you have a wedding to attend in the near future, I'd be hesitant to buy one now. I honestly think that only makes sense if you have a VERY spartan closet (and know definitively that nothing you have would work) and/or have a body type that proves very difficult to dress (and therefore need to seize upon something that works if/when you find it). From what I've seen of your closet and your figure, neither of these are true. And you just don't quite know WHAT you'll be in the mood for when an actual wedding arises if you buy one now, especially given how you've recognized your style has shifted a bit just in the past few months. Once you have an event to attend, you'll also have more relevant details (time, location, size, etc) that will likely inform your purchase. Finally, waiting frees up funds to spend on items you need/want for use RIGHT NOW! Just my two cents, of course, but I'm on Team Use What You've Got/Wait To Shop. The one exception, in my mind, would be a LBD, if you don't own one and happen to come across a great one: then, BUY, particularly if a classic style. You'll always use it!