I can relate. I wear a 36D, and I have that in-between problem of sometimes fitting into a C. It's hard to explain, but when I wear a shirt that fits, my upper portion reminds me of those black and white movies with Rita Hayworth. It's that triangle shape that most bras push my chest into that gets to me, so I know what that issue is like.
I have an hourglass figure, meaning I have hips and an ass. So I get annoyed with undergarments at both ends. Not exactly because I am large, just endowed, and believe me, most times, it's no blessing.
Underwires are not exactly healthy, since they cut into the muscle under the fat and usually leave a mark. The size and weight, unbeknownst to most men, will cause the muscles in the upper back to be pulled to where the muscles in the shoulders should be and the shoulder muscles where the upper chest muscles are and so forth. So it's either a boob sling or a cage. It's either hanging low or straps cutting into your shoulders.
It's boobs like mine that make me wish I was in Africa, where it wasn't such a big deal.