underwire fits well but cloth around boob is very loose, too much fabric

hi there i took the plunge and ordered the curvy kate emily on ebay. i ordered 34g, but then realized that im a 34ff. decided to wear bra anyway. the underwire fits fantastically, but there is a lot of loose fabric in the cup area. does this mean my cup size is off or is this problem specific to that bra? i was thrown off because the underwire part fits so well.