Anyone who tells you they wear a cup size of EEEE is lying. No brassiere manufacturer, on both sides of the Atlantic, uses that cup size. Sounds like someone who knows nothing pretending. The same with a DDDD. The last time a DDDD was made was at least 25 years ago. Since then most manufacters don't even do DDD, they call them E or, depending on the maker, an F. The sizes often run ...C, D, DD, F, G or some makers use...C, D, E, F, G, GG, H, and some go C, D, DD, F, FF, G, GG,...you get the idea. No rhyme or reason to it.
The DDDD hasn't been used even by the Sears catalog in at least 25 years. The makers all use F or G depending on how they do their sizes. Ignore someone who says they are a EEEE. No such thing. Now that would probably be a real size of H or G or FF depending on who makes the bra. Gets even wilder on sizes on the largest cups. I wear an H and sometimes a HH or even an I depending on who makes it and my time of the month. They don't even make a bra my mother can wear. All of hers are custom made.