Look at it this way: more than likely he wants to see you guys settle into your "adult lives" (get steady careers and start building your futures) before he makes any sort of commitment. Those kinds of things can drastically change a person. Hell, I got a job that was a graveyard shift and as soon as I was able to switch to days my boyfriend said "thank god because that sleep schedule made you batshit crazy."

Here's what I did: I'm 26. Ideally I want to be married and start having kids before I'm 30. I absolutely love my boyfriend and would love to have that future with him, but I understand he's his own person and may feel differently. So, when he was talking about some plans we have to move out of state and he will be going back to school, I laid out my timeline. In essence I said, "I don't want to put a timeline on our relationship because I don't think that's healthy. That said, you know I want to be married and have kids and ideally I'd like to have my first kid before I'm 30. As much as I love you, I don't want to waste time waiting around for someone who doesn't feel the same. If after a year after our move you aren't certain you see that future with me, I'd like to know so I can move on." (By this point we will have been together over 3 years.) He completely agreed. He even said "if I don't know by that point then it's probably not meant to be." He's reassured me that he sees me in his future until he explicitly states he doesn't. He's a guy! Guys don't generally say "when we're married" or "our kids" until they've put a ring on it.

I communicated how I felt without laying on him the expectations of "I must have a ring by this point in time or else!" It was just, hey here's what I want in life and if after this amount of time you don't see that with me then that's cool but just let me know!

Just broach the topic and see where things go from there.