Does wanting a child put stress on your relationship?

So I've had baby fever for a long time now! Me and my SO have been together for almost 4 years but we are fairly young! He doesn't want children till another 3 years approximately and he doesn't want to be engaged till then either. It's just making me feel rejected and emotional! I really respect his decision because I know when he's ready it'll be more than perfect but I just feel he's a child. He's 20 years old and turns 21 in June and when he's not working he's stuck on Xbox all day playing games! He's just stuck in this teenage world and isn't ready to grow up yet. He's still young yes but I just wish maybe things were a little different. He's not ready for engagement and for some reason I can't understand! Is anyone else's SO like this and what was the reason? One of my main goals is to have a family with this man and married someday hut I always question if it'll happen! I've got off Birth Control because it really wasn't for me and he won't buy condoms at all. It's just constant excuses like 'I don't have time' but we would be around town passing stores where they are available. He's a unresponsible man who doesn't want to use protection! He isn't going to force me on Birth Control he agrees with me but he doesn't want a child and won't do anything to prevent it.