Having a different last name from my daughter?

Kayla
So I got married back in January and I've not changed my name yet. I still have my old married name and my 6 year old us the same last name. I'm considering either changing my last name to my new married name or hyphenating the 2. My ex isn't in my daughters life at all  if I'm sure he wouldn't let me change her last name. 
Anyone else in this situation?
My new little one will have my husbands last name.