Wow, at 19 I never thought about marriage once... I was too busy...
The fighting thing is a component of some relationships but if it is a lot I would be a little concerned. However you are still young and as time goes by we all (well most of us) calm down a bit.
Anyways congrats and good luck... Marriage has a lot of pluses if you are with the right One... And if you feel this way at 19 on top of being so well grounded it sounds like you are on to something.
Good luck.