I married when I was 20, by 25 I was divorced, now I am not so sure that I ever want to marry again, paper does not mean nothing to me.
I say, stick with the guy if he makes you happy. There is not much more you can ask for, but the guy who makes his woman happy.
How important is signing the paper for you? What will it change for you?
Probably not much.
Stay with him, and if ever things go bad, at least you won't have to go to court like I did and fight for you portion of the assets.
Pay attention to your finances, don't give him your every penny, and overall try to keep things 50/50. there will be less drama, if you ever split up.
And if you end up having kids with him, courts will give you child support, regardles of your marital status.
Go for it! Be happy while it lasts. Nobody can guarantee you that if you marry someone else that you will be happily married.