How do I respond?

My fiancée and I have been together for over two years.Things are awesome, together we are planning our wedding, and also talking about the future.

When I bring up baby making plans he at first said lets wait six years, and Then he changed his mind to tell me he wants to have a kid after we get married. Most of the time when I have worries I talk to him about how I feel, its almost like he shuts down on me.

Like he just agrees with whatever I want, or whatever i say. I genuinely care about his feelings, and I want to compromise but i also don’t know why he acts this way