[Malina]

If you measure right under your bust what do you get? What about over the widest part of your bust, I bet that will put speculation at rest

I'm betting you're a 32C or 32D, which would explain why the larger bandsize bras with smaller cups fit you. But your perfect fit is likely a smaller band and a larger cup size. Up until I got to this site, I've been mis-measuring myself in the band, as well.