pregnancy

I have been with my boyfriend for 9 months he's 30 and I'm 19 I'll be 20 soon and we don't use any protection and he always tells me how bad he wants another baby(he has a 4 yr old with his ex of 9 years) I dunno wether to believe or if it's just a ploy to get me stuck with him I need your thoughts. I want to settle down soon and start a family but I don't know if he's serious or if it's just a game for him. I've asked and he says he's serious but I just don't know...