Am I crazy? Lol

So I am about to be 21. And my boyfriend is 22. We have been together for 3 years and some. I am completely in love with him and he feels the same way. But I feel like we aren't going anywhere. I would LOVE to be engaged but when talk about it he is always saying we are too young. But too young to me is no excuse. I know I'm in love with him and I know he feels the same, so why is age in the way? I have always felt as though I'm very mature for my age. My parents and friends have said the same about me very often. I also think so heartfelt on the idea of having a baby. I feel as though I am so ready and I have always wanted to be a young mother. Just like my mom was. But of course my bf is completely the opposite. He does not want to have a baby at all. Lolol What do I do?!