As a wannabe CD with boobs, I now need to wear a bra for nipple modesty and uplift, but I have had great difficulty in getting my size, which is around 40" band, A or AA cup.
Most lingerie sites don't stock small cup sizes above 38" band. I tried to get fitted at a local store, but was turned away, even though I was already wearing a visible bra under my shirt. This bra was one of my sister's, worn with an extender.
These band extenders don't really work, they set your bra straps too wide and you can't seat them nicely across your shoulders.
My solution has been to buy quarter cup bras (e.g. from pabo.com). These bras are designed to give support to busty women, whilst exposing the nipples. Thus the XL size is about 40" band size, but with A sized cups. Also, the cups are set wide apart.
I find that I slip easily into such bras, and fill the cups nicely, without the nipples popping out. Also they are normally very pretty and lacy bras!