Going for a custom made dress is the equivalent of getting the silhouette, fabric and fit you want all at once. And you're not confined to using only wedding dress patterns. Try whatever pattern suits you in the particular fabric you want. Plus, there are plenty of resources for vintage patterns online. If you do decide to have your dress made have your designer or dressmaker construct a muslin first. That's a cloth pattern of the actual wedding dress where all the fine tuning and fitting is done before ever cutting into the actual fabric. That way once you do take the actual cut, all the bugs have been worked out three dimensionally and there are no big surprises.
RETRO REPRO
A couple weeks back we explored going with real deal vintage on your wedding day. If you love the silhouettes of yesteryear consider retro reproduction versus the time involved in hunting down an actual vintage dress in your size. Defined, vintage fashion is anything over 20-25 years-old. While using a pattern and recreating a vintage look isn't wearing an actual gown that has survived the ages, you will be replicating as close a look as you can get. And because women back in your grandma's day dressed up and much of what they wore was sewn, golden oldies like these are still available through companies like So Vintage , a treasure trove of 20th century patterns--most spanning the post war boom of weddings, babies and a fully stocked sewing room. For me these have been the muses and backbone of all my collections. Yes, the patterns are one-of-a-kind which means one size only but they have an online resource with instructions on how to size a pattern up or down (convenient for your designer or dressmaker).