I recently had a rhinoplasty & septoplasty, its almost 6 months & on one of my nostrils I still can hardly breath. Is this normal?

Usually by the 6th month the breathing is most definitely restored.  In fact, most patients notice improved breathing within a month to two months of surgery if they had difficulty breathing beforehand.  I would suggest that you have a follow up with your surgeon and ask his advice or determine if the lack of airway is indeed from a deviated septum, redundant mucosa or enlarged or redundant turbinates.  I do not know from your question if this is a constant occurrence or if this is at certain times of the day, while the body is horizontal or after exercise. These factors can also hinder breathing due to engorged tissue due to increased blood flow.