It’s such a tough decision @Lovehearts33 , it’s easy to speculate from the sidelines but hard to break up a relationship when you don’t really want to. Maybe the compromise is to step back from this issue in your own mind, take the time to quietly come to terms with the possibility he’s not the one for you but don’t do anything sudden. Take care of yourself, let him take the lead and let his “steer” for a while, give yourself a break.
I’m not suggesting you become sullen and withdrawn instead maybe try enjoying the relationship for what it is now, be fun, have fun, be light and think about what your ideal relationship would look like, with him or with someone else. It’s so easy to become so fixated on wanting a family and wanting someone to propose that we sometimes forget to think about what we really want. Whatever happens, whatever you decide, it will be best to leave the relationship amicably or to choose it and accept the uncertainty.
He is young, he will mature, BUT, that’s not your concern-you are not his mother. Getting married and having children is something he should feel excited by, but he needs space to feel that. Crucially, he ideally needs to wonder if he’s good enough for YOU, if YOU will agree to it. So try getting into the headspace of what life looks like with having children later, or with someone else or even not having children at all (some of the happiest people I know ended up on this route).
I know this feels so unfair, but the truth is no one owes anyone else children or marriage, no matter how good and kind they’ve been. Just try being gloriously, unashamedly, happily selfish and self serving and stop trying to control him. Easier said than done but I promise it will pay off.