I think most trans women end up with the nipple and areola size that they would have had if they'd developed as girls, much like breast size; I haven't measured mine, but the nipples are about 4X the size they were when I started, and areolae more like 10X the size.
(My wife is a 36J, with corresponding nipples and areolae, so I swear I'm always going to feel small by comparison!)