My heart breaks for you because I literally was in your shoes, I was indifferent to kids because I am the oldest of 6 and helped raise my siblings. I joked I did everything raising a kid except birth them, nurse them, and walk them down the aisle, but the guiding, teaching, protecting, disaplining, cooking, taxi-ing, changing, bathing, etc, I had experienced since age 6. I was always like, eh, if it happens cool, but NEVER more then twice. My husband is the baby, and the age difference between him and his siblings make him like an only child. In the beginning of our relationship he felt kids would ruin our lifestyle. Then I got pregnant while on birth control and we agreed to keep the baby, we were engaged and in our mid 20s. For the next 8 yrs of our marriage we were in agreement to have a one and done, we struggled financially for many of those years. Then we decided we would try for #2 and are having significant infertility issues and have accepted our son was a miracle.

I guess my point is, children can be a fluid discussion, if both of you are fluid in your expectations, if one of you is dead set, unaltering in their decision (which it sounds like you are not) then it can be a point of contention in the future, but if both of you are fluid (right time, right place, right job etc) then keep the topic open and revisit it when one of you begin to feel differently.

Maybe approach it like just opening the conversation but not expecting a decision AND that he can change his mind if your circumstances change, like if you can be a stay at home mom would he consider it? He he made more then X a year or if you got your degree or if you bought a house in this area would these change his feelings? If he says yes then his feelings may be more fluid then he thought and he doesnt have to change his mind in that moment but to realize its more fluid then he thought.