We had a second baby just becasue we wanted one. We spent alot of time worrying about when was the right time and could we afford it and then we realised that if we kept thinking that way we would never have one. So we ended up taking a while to fall pregnant but now we do have two wonderful children but we still don't own a house and that's ok. We also make it through every month somehow and we are not not living on the breadline or antyhing like that eventhough we really thought we would struggle. The only thing we did differently to try and save was not use disposable nappies and that has helped alot. And now we have decided to have a 3rd baby and our situation has not changed much financially or with regards to a house etc.
Good luck with your decision. Go with what your heart tells you not your head.