I want a baby

Mo
My boyfriend and I have been together for a year and a half. We are looking at apartments together right now and talking about our future. We love each other very much and we do everything together and care very deeply for one another. 
​When we first started dating he had said he wanted to get married and have kids and I said I didn't (because I honestly didn't) and over time he started saying that he didn't want to get married or have kids either. But the more I get to know him and love him and grow with him. It makes me want a baby! His baby. So bad. Not right now of course but someday. How do I tell him I changed my mind or do I wait for the time to come? 
I don't want to get really involved with someone and make a life with them if we can't agree on something really big like this. 
​When should I say it and how and should I make it a big deal or casually be like "you know a baby wouldn't be so bad..." 
​Thoughts?