Time for a baby???

My boyfriend and I have been together for a while now. He already has 3 daughters from a previous relationship. I have always wanted to have a baby younger (I'm 22). I know I am mature enough, but I'm not sure about financially if I'm ready. He has had next to nothing raising his other daughters before because neither of them worked, however we both do now. I want a baby but I'm just so scared about the financial aspect. I've known people to be in my situation then get it all together during the 9 months but still. I just don't know what to do. I want a baby and I feel ready but I'm so nervous too.