You are the same size as me. I am not happy with the amount I have spent on bras in the last couple of years, especially as I bought some that fit for a while and no longer fit. Maybe the forum should do a bra exchange.
I think more people than we think are unusual sizes, it is just that people are conditioned to think that you don't need a cup bigger than a D or a DD. Or a band size smaller than a 34. Many people end up wearing bras that don't fit. And most stores (with a few exceptions) don't care because they can cram most of the market into a narrow range of sizes.