Does motherhood define you?

Brittany
I ask this because I was telling a friend of mine last night the idea I had for a maternity shoot. I said I wanted it to be fun and vintage-y and NOT all about the belly. 
She came back with, that it will always be about the belly and always about the baby and that I will just have to get used to it. Basically implying that my sense of identity will be lost once our child is born. 
I told her I disagreed and that while being a mother will impact my life, it will not define me, nor be the center of my universe. Will my child be important to me? Absolutely! But it will not define who I am. 
She is kind of a "know it all" who always has to interject her opinion, whether it is warranted or not... So I blew it off. But now it has me thinking how others might feel. 
Thoughts?