Great insights! I commiserate with those who struggle to find bras that fit. Any fit issue is a pain.
I don't love shopping for bras, but I don't hate it, either -- and I fall into the rather-hard-to-fit category. Small band (30) and small cup. (D in some brands, e.g.. just barely in the Simone Perele Caressence, which I own and love) and C in others. Also, widely spaced breasts with little projection. Yes, I am the girl whose boyfriend once asked me, after I boasted of some accomplishment, "Do you want a medal, or a chest to pin it on?"
I used to get shoved into 32 A or B bras and it was ridiculous -- I was always spilling out of them in the craziest ways. But it was all because that's what the shops carried, and I looked "small" to the SAs. Meanwhile, the ones sold for petites are just too small for me. The whole fit is off somehow.
Also, I have a penchant for pretty bras so don't really like the utilitarian models, and sometimes that is all that's available in smaller sizes.
Plus, I live in a town where the options for my size range are few and far between.
So I have simply decided that bra shopping is its own "thing." I devote a day to it once a year in one of the major cities I travel to. And that is that. I find a well stocked shop and spend a few hours in a fitting room. To my mind, it's worth it.