[mochaccino]

It's progesterone that grows milk ducts and prolactin that encourage milk production. Growing more milk ducts or larger milk ducts isn't a bad thing as long as it doesn't happen at the expense of fat. Milk ducts are increased at the expense of fat during pregnancy and lactation, but that's not likely to happen during NBE, unless you focus only on raising progesterone and prolactin without raising estrogen. Some women do grow by increasing progesterone alone, but these women all have naturally low progesterone and normal or high estrogen, usually due to PCOS.