P.P.
I found that things change over time. I wouldn't press the issue until you get your way though but will offer some other advice. You are blessed with three children and he has a point about the cost and time involved in expanding the family. Men tend to think about the money part which is not a bad thing. My husband and I agreed to two kids and after our first we said if we had two girls then we'd for sure try for a boy. On our way home from the hospital after my most recent child I told my husband that I thought I was done and he agreed with me. I told him that I wasn't 100% sure if that's what I want so we agreed to discuss it in 6-9 months and I'll just keep asking every 3-6 months or so after. Maybe you can periodically keep evaluating it to see if he'll change his mind. I just wouldn't hound him on it. Just because he doesn't want another one doesn't me he rules or just because you want another one means you rule. One of you will have to bend. You can do a pro and con list. You each take a piece of paper divide into two columns and write in the pros and cons of having another baby and compare your notes. Hopefully this will help in the decision making. Good luck to you and I'm eager to hear what happens.