Last name

Please dont be mean

I am having trouble deciding last name I am not married but have been with my man going on 6 years and 3 months I love him and I hope we will always be together but I was always raised if your not married baby has my last name not the father I have a 7 year old that has my last name but her father was in prison and still is and her last name is mine and would have been regardless but idk what to do about this time sould I give the baby my last name or his ??

We are not engaged or anything we just live together 2 months out of a year bc he works outta state