I think what we're trying to say is that it's not fair to blame your husband for the way you feel about having another baby. I'm sure it is a difficult thing for you to come to terms with, it's obviously a big part of your life plan that may not happen now. Focusing on coming to terms with that in yourself rather than trying to convince your DH is probably what you need to do.
Just wanted to add, it's important for your current children that you find a way to accept it. I remember my mother once told me how devastated she was that she didn't have more children (she had 2 and wanted 4) - as a kid I felt really upset that we didn't make her happy.
Your DH might come around though - if money is an issue you might need to come up with a way of addressing that. Maybe you go back to work part time for 6-12months before having another or agree to go back to work part time after the next one is 1yo. I think that's where your compromise might need to be if he does open up to the idea of having another baby.