Is this crazy?

My SO and I have been together for almost 6 years. We have a son together and recently found out we are expecting or second child. We planned this pregnancy and I’m not so excited about having to tell my parents as my Dad has been very adamant about us being married before having another child. My mom on the other hand hasn’t really said that she does want another grandchild though. I do want us to get married and we are in the same page but I really wanted another child and I don’t see what’s so bad with that. I feel my dad has only said that because we have kids and that marriage will somehow make us stay together but he has even talked of divorcing my mom before and I don’t feel that I should have to be married just to have kids. Is that so weird of me? I just know when i tell my Dad he is going to be mad and I’m not ready to deal with that yet. I don’t want to wait super long to tell him but I also don’t want any stress.