this is a most interesting thread.
I myself wear a 30HH (cleo-Panache tango-ii plunge and Marcie balconet; I also wear a CurvyKate tease me, but it's a lot shallower and so I get a pushed-up slightly spilling effect in it)

My breast root is a little wider so I don't have the Omega boobies, though I often had difficulty getting a bra to fit (like "freya" an entire company of painful cutting in across the top of the breast)

my Best friend has omega boobies to the max though. We are both short and Busty, and wear the same size clothes... but we are such different shapes Underneath. It's quite Astounding to think modern mass produced clothing fits the pair of us equally well... which is to say... Kinda sorta, It'll do.

I am hoping to eventually make a garment that cinches the waist like a traditional corset, but has more modern cups so it doesn't look so odd under dresses. So I shall read along any developments you come up with...

*I just realised this was a year OLD! boo! how did it go ?

Just wanted to update with you on my progress since we're both having the same issues. I found that I got a better result with an underwire in the same shape as my original best fit but was about two sizes smaller. Also since I can't get my hands on industrial strength stainless steel underwires like the big lingerie companies, I doubled up the ones that are readily available to home sewers and got the same result strength. I reconfigured the cup again- a side power bar leading to a padded strap, four lower cup pieces and a contoured upper cup piece (think Parfaits by Affinitas Charlotte bra, only with more pieces). Now the only problems I'm dealing with are (1) a flattening plane across the upper chest which causes a quad boob effect and (2) not as much lift as I would like. To solve problem (1), I'm going to spread and curve the upper portions of the lower cup pieces and spread the upper cup. For problem (2), I'm going to try a sturdier but still thin padding with rigilene supporting the vertical seams. Keep your fingers crossed that it works. Good luck to you too!!!

This is a great question and study. I recently purchased a 1950's-era vintage torpedo bra thinking it would solve all of my problems, ie, keep the same under bust circumference (36) and mold my boobs (D+) into a period-correct shape for 40's/50's dresses. I was so wrong!
My breast tissue didn't conform into the tips of the torpedos, even though I thought I'd purchased the correct size and I have ample tissue to fill it out. My breasts are rounded and even in a conical bra, they stayed rounded, much fuller at the base. (Much to my surprise.) So I will be following this thread and any related bra articles with interest.

Ceciled, you might find some solution in Bra makers manual by Beverly Johnson on page 135-137. There she is writing about alterations to the bridge. If the bridge is too narrow in the bottom it might tip out from the body on the top.
I have about the same shape and problem, but splitting the bridge a little at the bottom made the bridge come closer to my body. Don´t ask me why but it helped!

Yes! I would definitely say it's an omega and am dying to get Beverly Johnson's books. I've made numerous bras and none of them fit right. With each one I'm finding out I'm even bigger in the cup size range. Some would be happy with this, but it's actually not fun when you can't find your size anywhere. Now I'm pretty sure I'm either a 34O or P US size. Good luck finding that anywhere. I haven't given up but with the number of hours I spent trying to figure it out, not much else was getting made. I made a few soft bras that fit but just don't give the support I need. Being short in the waist, no lift is not flattering. You can't see your waistline if your boobs hang too low. So right now I'm defaulting back to my nursing bras which give me the best support even if they are a little small in the cup. Also have had to take the band in. I've done a lot of reading on the wrong bra size and how back and armpit fat can actually be breast fat that migrated away because of ill fitting bras. So you can recuperate volume by getting the right size and scooping from back to front. Can even help lift breasts again. I think the fact some wires dig into my ribs right under the breast is also part of the short waist problem. I don't have that space for things to lay completely flat.

I'm in the same position, extremely large bust/smaller ribcage (37M/N, which people think can't exist naturally). You may need a smaller wire and have to ease in the proper cup on the underwire line to make the bra work. If the mass of your breast tissue is small at the base but expands just after (similar to a balloon held against a flat surface), you may have an "Omega" shape. I have gotten alot of helpful answers about how to fit this (read: my) type of bust from the Bra Maker's Manual by Beverly Johnson.

You may even need to make the lower cup in more than three pieces. The more seams you have, the finer the fit. The prototype I'm working on didn't give me the lift I desire but when I subtracted width from the other three panels to create/add a fourth panel, everything started to curve up and round out better for my shape (yea no torpedo boob!)

Also try buying, or at the very least taking pictures, of bras you like the end result shaping of. I like the look of Ewa Michalak bras, especially the CHP and the CH styles. Even though it's a custom designer bra company, I still fall out of the range of their sizing. After studying the pictures and looking at some physically, i was able to see what direction I needed to go in. Plus looking at the fabrics they chose assisted in my being more selective about the fabrics I would use. Fabric makes a difference too.