If you cannot wear strapless things everyday then why would you buy a strapless wedding dress? This is one of the most important days of your life. And you will look ridiculous trying to pull up your gown every five minutes so just save yourself the trouble and buy a beautiful dress with straps to keep your girls in place. Strapless dresses are in no way better or fancier or more elegant and not everyone can pull them off, I can't and I know this so I stay away.
Try on multiple different kinds of dresses and take someone with you that always tells you the truth.