Fiancé wants a baby and I'm not ready yet

My fiancé and I talked today. He said he wants to start trying for a baby. Don't get me wrong I want a little family too!! But not right now. Maybe in another year or so because I am still in college and I atleast want to be through with it and have my career started. I told him that and he said okay but I can tell he's upset. He's just kind of moping around and acting different. I feel bad. Has anyone been through this? What do I do?