Girls, do you ever have trouble finding a dress that fits right..around the area?

ok..so, first of..im a girl, 16, and i have DD's. i can NEVER find a dress that fits right, around my area. like you know how most dresses have like a bra in them, to hold up your so you dont have to wear a bra..well, every single dress i try on..its not big enough up top. i try larger sizes & its still the same..its not just dresses either, i have a singlet that fits great but it has a built in bra..and that doesn't even cover half my -_- my cousin has E's..and she can NEVER find anything that fits her, she wear oversized t-shirts most of the time.. my aunt has FF, (they are real lol..i come from a family of big s) and she can hardly ever find anything.. is it just Australia? or something? do they not make clothes for girl with bigger ? anyone have this problem?