it's just so difficult to find the perfect size KristinaM.
i suggest that if you ever find a top that fits you perfectly, buy a few of them and always use the same manufacturer.
have you tried strechy tops (i.e. cotton mix with lycra etc). it is essential taht your bra fits correctly, otherwise you'll never win.
also shirts (the slightly fitted ones that accentuate your waist) might be a good bet but consider having them altered at the drycleaners or a dress maker around the waist.
what about strechy cardigans, would that be an option for you? or the type with a belt to accentuate your waist.