My baby will have 2 last names no middle

If I'm thinking of names to give my little girl. I want to have my bfs last name and my last name since he is Puerto Rican and most people do that when they have kids. But no middle name. My bf doesn't have a middle name just 2 last names. His mother's last name and father's last name. Is it weird I don't want a middle name for her? I honestly can't think of a middle name to go with her first name I picked and I think it will be way too long if I put a middle name.