Baby fever

I'm 19 and my bf is 24. We been together for 3years now and i want a baby so bad ! He has a 6 year old daughter and I don't want them to be so far apart :( I really love him he asked me a few times to have a baby but I always think he's playing . He's a good father, he recently got a good job and I'm planning to get my ged .. how do I convince him to having a baby ?!! Do you think we're ready ?!