hi. i often find it to find nursing bras, being of a larger bust myself it can be very difficult.
my underwired bra size is a 38h but when buying nursing bras i've found that due to the design of drop cup bras i have had to buy 38j's instead and i've still found that they don't fit brilliantly.
my advise foe buying maternity and nursing bras is to shop around, look on the web and in shops and always be aware that although they may fit when you try them on in the shop, they will stretch within a day where you are always having to feed baby.
some good makes i've found are
emma jane (drop cup, the zip cup hurts if you catch you skin in it)
royce (any of them, they have some very pretty ones and go up to a jj cup)
and freya rosalie (although they only go to an h cup.
i hope this helps and good luck, enjoy your baby cause they grow to fast. xxx