The gals blessed up top think they don't stand a chance.
The less endowed think they need a larger bust to "hold it up".
Both are wrong.
To understand why, let's get into "fashion engineering mode". There is a legitimate concern at play here. Your special day is no time to feel self-conscious, of course. Here's the good news in a nutshell:
If your bustline is sized AND supported properly AND the weight of your dress is supported at the waistline...
YOU'RE GOOD TO GO!!!!!
For the bustier among us, additional structure may even be necessary in the cup itself. This isn't something you'll come across in your day-to-day wardrobe, but for your well-made gown? Certainly doable. This is somewhat of an advanced technique and not the sort of thing you'll typically find in chain bridal stores or in prom/maids/non-bridal dresses (other than luxury designers, anyway).
But the most important element at play overall here, in my opinion, is the fit at your waist. If you are secure there, the dress won't have anywhere to fall.
You may see what I like to call the "safety belt" inside the gown and along the natural waistline. The "waist stay" can be anything from a 1" grosgrain ribbon to an elastic band or even an entire inner corset. These are the kinds of details that effect price point, and I'm sure one can now appreciate why the value of a gown doesn't lie solely with the styling on the exterior.
Read more about waist stays.
So when we're talking about custom design, and you have the option to make sure these structural elements are present, consider yourself invited to the FULL array of amazing strapless styles!
Disclaimer: Even though I hold all this to be as true as the science of gravity itself, an equally powerful truth has revealed itself in my experience. If a woman sees a flaw in the mirror, I generally treat it as though it's there (even when I'm looking at a perfect body). Why? My first point: if there's something you're self-conscious about already, I'll do everything in my power to take that concern off the table entirely. I can promise you up one side and down the other that your dress will stay put. But if you've been let down before, had your share of wardrobe malfunctions, you might subconsciously tug at your neckline even with a perfect fit. So consider this an educational post, but with no intent to persuade you. This topic is a matter of personal preference, of course!
Happy strapless daydreams,