@Imammaaama I haven't RTFT, only your replies.
You're not wrong to want to be married, and to want him to propose.
And I get the sense that wanting him to propose is less about wanting a perfect romantic proposal like you see in the movies and more about wanting him to demonstrate that he is as committed to you as you are to him. Because it sounds like you've driven every other major decision the two of you have made.
The thing is though, it's quite easy to twist a man's arm to buy a house (which is, after all, a valuable asset for him), and even to have a baby (men don't like to take responsibility for contraception). So a lot of the time if you say, "let's buy a house, I've booked three viewings for next week", or, "I want a baby, I'm going to come off the pill and let's see what happens", they will just go along with it. But if you expect them to actually play an equal role in the decision making process, let alone take the lead, they just never will.
Assuming the truth isn't that he doesn't want to get married because he doesn't want to be legally tied to you (which is less likely if you own property together), you could probably persuade him down the aisle. But you'll have to say, "Right, I've had enough of waiting, we're getting married next October, I've booked the registry office, here's a list of reception venues, do you want to help me pick one or shall I just go ahead and organise the whole thing myself?" You probably won't get an engagement ring either, unless you buy it yourself.
The thing is, you can't make him do these things. He has to want to do them, and it sounds like he just isn't bothered.
Different situation, but I recently forced someone to apologise to me for something. I absolutely deserved that apology and I was determined to get it, but in retrospect it wasn't really worth it because it wasn't spontaneous or heartfelt. And now I have to pretend to have moved on, forgive and forget, it's all ancient history, whatever, when actually it still rankles and probably always will. And that's how I think you'll feel if you twist his arm to get married and march him down the aisle. You'll always resent him a bit.
As for whether it's reason enough to leave, only you can make that decision. I don't know if I'd break up my child's family over it, but it probably depends on what the rest of your relationship is like.
If you don't want to leave him over it then I would at least get some legal advice to see whether marriage would put you in a stronger position, and what, if anything, you can do to give yourself more security without it. (Life insurance, wills, powers of attorney, pensions etc.) If you think you really ought to be legally married for those reasons, perhaps just frog marching him down to the registry office on a Tuesday lunchtime is the best outcome you can hope for.