Yes I think it is big but why most people measure with BP ?
I think I am close to your size and my girlfriend says a lot of time I m big.
I am in length 18cm NBP ( 19 BP) and 15cm at the middle, 16 cm at the base. What do you think for me ? (Sorry for my english I am french :) ) My height is 179cm.
But beyond my ratio, 18x15 NBP (19x16 BP) is it in the average, big, very big/huge category ?