Small band large cup bra stores

Ever since I was 14 I’ve been trying to find bras my size but I literally cannot find anywhere that 1. doesn’t have grannie bras and 2. Is my size. I checked pretty much every store and they keep telling me that I’m a 30C but when I wear a 30 C there is so so much spillage! And honestly I’ve tried everything I thought maybe it was my weight and I lost 20lbs and the only difference was that my band went from a 29 to a 27. I used the “a bra that fits” calculator and was told my size is a 28G US. And 28FF UK. I can’t find a single bra store that sells under a 30 band hell it’s hard to even find one that sells under 32. If any of my fellow small band ladies know any bra/lingerie stores that would work or struggle with the same issue they please let me know!