You can get now to the immigration office and bring with you the letter of wedding date as well other documents, i'm sure you could get an extension. Try it asap. Otherwise you would be asked to go back and do the family reunion visa which takes some time! At least now you are in a legal statut with marriage so you can manage it !
Advise don't get yourself to a Duldung! As a husband it is awfull, try to avoid it ! Best luck