I don't know what is the significance of marriage for you, except symbolic. IMO the truly critical point is having kids. You probably want to have stable income before that.

Regarding things you're "just supposed to know": same thing happens to me with my wife. Haven't stopped us from being together for 10 years and raising a 4 year old son. Different people see things differently and have different assumptions on what is "obvious". The important thing is being mutually patient and forgiving (I know it's easier said than done, but it's doable).

Regarding the "extra feeling". Don't really know what to tell you. It is difficult to compare emotional experiences of different people. When our relationship started, it was mad, passionate infatuation. Now it's something calmer but it is obvious to me we love each other.

I had few relationships apart from my wife and virtually no serious relationships. Never bothered me.