Idk what to do

If you already have a kid with ur significant other & they know u want another but they don’t would u still be most likely marry them? I’m engaged to him & our baby we have now came to a complete surprise & now that I know we work great together as parents just as much as partners I really want another. Every time I ask & he says ‘no’ it’s crushes me a little. I’m a only child & ive always has my mind made up that I’m not gonna just have one but now I’m stuck in this situation. Idk what would you guys do?