Last Name!?

Meghan • Leighton Carter: 12-23-2016. ❤️ Aquarius.
So me and my boyfriend are expecting a baby girl in December. We aren't married, but are planning on it in the near future. My thing is, I never wanted to give my child a different last name than if I'm not married when she comes (which I won't be), she will keep my last name. 
My question hard is it to change a child's last name after I get married? Should it match mine, or give her his? Feel free to comment below with whatever advice or stories you have. Thanks ladies! 

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