Re: He won't propose... says he is "Working on it"
Why are you moving forward with all these plans for things you do not want unless married, when you are NOT married? Why would you even discuss buying a house together if that's something you feel comes with marriage? You are sending the message that your words don't mean much--you say you won't do x, y, or z without marriage, but you ARE doing those things. He will not take your words seriously if you do not.
Think long and hard about this. Your position has pros and cons.
Con: he may let you walk away if you take a stand and refuse to move forward on the house, etc, without being married (which, if that is really how he feels about you, is actually a good thing, but you need to be ready for it!)
Pros: all the legal protection of marriage for your financial position. This works both ways, for him as well as for you. You are spending money that you may never recover on a house if you share it with him without marriage or some other form of legal protection. Purchases for the house, repairs, etc., and not just the price of the house or the mortgage payments--all of that will be hidden and murky if you don't clarify it in writing or get married, in which case it will be communal property, evenly divided (in most cases).
Honestly, if marriage is important to you, stop all forward movement until you are married. Just tell him--we get married at the courthouse tomorrow and then we can resume our plans. It would be unwise (in your position) to start planning a wedding unless you are willing to put everything else on hold while waiting to be actually married. If you mean what you say, then you should get married first, plan the house buying for after that. You need to decide if you want to stay with him without marriage, without buying a house, etc.
If you aren't sure of his intentions, then make sure, because otherwise you will be really unhappy if his intentions turn out to be something other than you thought. I don't trust a guy who says he will marry [you] someday. . . Total stall tactic for something he's clearly unwilling to do. Either he's ready or he's not. Again, you just need to be prepared for his answer, and unwilling to accept anything less than what you want, if he's strung you along this far. Good luck.