Wanting a family taking a toll on our relationship?

I've been with my SO for 3 1/2 years and since over a year now I have horrible baby fever! I have a urge to have a family and we can't.. I'm finishing up school with a possible another year left,I don't have a job or a car and I currently live home! He has a job at the airport for full time and he has a car but he's going into the process of being a Police Officer! This isn't the time to have a baby at all but this doesn't stop me from wanting it and constantly talking about it with my SO. Also I have to add in that we live a hour away from each other and always have! We see each other on the weekends! So what can I do?! I just feel like I feel differently about our relationship because I'm not getting my own way.. (I know it isn't right but my baby fever and mind) He doesn't want to be engaged for another 3 years and doesn't want a family till then.. It just feels as I'm rejected and it ends with me being upset and in a bad mood! I do want a family with him and I want to marry him someday I've always been sure but what can I do?! Any advice?! I don't want to start feeling different because we aren't in the position for a child and he isn't ready.. I wouldn't want to be with anyone else but then sometimes I feel like I'm convincing myself that and it scares me.. I get upset by when I bring it up he'll say 'I already know ;)' and he will ignore the topic a lot and say I always repeat myself :(