Slightly different situation as I have one DC and DH has two (one from a previous relationship plus our DC).
I wanted another child and DH didn't.
He had rational reasons but I also felt (I think understandably) that he was denying me something he had already.
We talked about it. A lot. One thing we learned was to do so when we were both calm and avoid the subject when heightened in any way. The "rows" rather than discussions were not helpful and built resentment rather than understanding.
I absolutely did not want this without his full support/commitment. Like a pp said I think having a child that one parent does not want is supremely selfish.
In the end he said if I really wanted another child he would be supportive (after about 2 years since the subject was raised).
The thing was that once he said that and it became my sole choice without his "buffer" I realised I didn't want another child.
We were happy. The children were happy. We'd just got through the endless waking nights and eldest DSC was starting school and youngest in nursery.
We were financially in a good place and starting to go on great holidays. I was working full time again and really enjoying my career and being successful both in terms of progression and earnings.
I realised just how much I (and DH and the children) would be giving up to go back to the baby years - and suddenly now I could do it, I just didn't want to.
I think in part our positions had become so entrenched I stopped really thinking about what I wanted vs what I valued.
Twenty years on and I don't regret not having another child.
I look at all we have done/achieved as a family and know that another child would have had a massive impact on that.
This was especially cemented as they became young adults. You think children are expensive re: childcare etc then you will have a rude awakening when they hit mid teens and beyond.
As is we've been able to support them both in a way that would not have been possible with three and us still having a a very considerable pension pot to look forward to when we retire (at 60 because we can afford to).
Then we hope to be grandparents some day who have the financial security and time to support the next generation of little Bread's :-)
If I was to go back to myself I would advise thinking MUCH longer term than just free childcare.
Hope that helps x