Last name

Emily

My boyfriend and I are at a stand still cause I don’t want the baby to have his last name because my other two children have my last name and I don’t want the baby to feel left out. We plan to get married next fall but I don’t want to take his last name just because “that’s tradition” and when I suggested we just choose a new one he gets mad. I’m just at a loss and don’t know what to do now. I’m 24+5 weeks