Too much thinking and not enough hands on! You definitely shouldn't worry about this, just look out the window and fly the plane! You can de-crab a 737-800w up to about 20kts of crosswind, but after that there's not enough aileron authority to keep the wings level so you crab the rest.
Even if the mains are not on the centre line, they soon will be as they're pointing the right way to make their way onto it! Just remember, the autobrake will effectively de-crab for you, just keep it going down the middle with the rudder and keep the into-wind aileron fully in at least until you get control taken off you by the skipper. the untidiness is his/her problem after that.