Fermentations are all different; some can take much longer than others. Take a gravity reading and make sure fermentation is still underway.  You do want to be careful that you do not have a stuck fermentation but if your gravity is progressing, you have activity and you don?t have an off smell you should continue to ferment .  The co2 from the fermentation is really the only thing protecting your wine because most of the so2 has been bound up by now.