Individuals who suffer from persistant nasal obstruction after septoplasty, nasal fracture, or cosmetic rhinoplasty may benefit from a Functional Rhinoplasty, the nasal operation that treats complex nasal obstruction.
There are several anatomic reasons for nasal obstruction, and certainly a deviated septum is one of them. Fixing it, however, doesn't always guarantee improved breathing, especially if you have narrow nasal valves that may have been aggravated by the trauma. It is quite possible that you did not benefit much from the septoplasty because a nasal valve problem was not addressed. (Ideally, nasal valve problems are diagnosed before surgery, so that the septoplasty and functional rhinoplasty can be performed together).
The Nasal Valve is the choke point of the nasal airway, and it tends to trump all others if it is narrowed because it is VERY sensitive to very small changes in size. During the procedure (also called a Nasal Valve Reconstruction), cartilage grafts are fashioned and placed in very specific areas to increase the size of the nasal valve cross-sectional area, and stabilize the valve so it is less likely to collapse with inspiration. Other manuevers, including suture methods to improve the valve area and tip-lifting methods have also been described to improve nasal valve narrowing, but the mainstay of therapy are spreader grafts and batten grafts.
A good thing about functional rhinoplasty is that it doesn't really affect the appearance of your nose and has no cosmetic benefit. It is purely a procedure to improve your breathing, and therefore is often covered by insurance. If there are cosmetic concerns, however, your rhinoplasty surgeon can easily piggyback the cosmetic changes in conjunction with the breathing portion (the cosmetic portion is self-pay since it is not a covered service). Therefore, you can look better and breathe better!
Sorry for the long answer, but my advice is to see an experienced rhinoplasty surgeon and have him/her examine your nose and nasal valves. You may be a candidate for correction of your complex nasal obstruction with a functional rhinoplasty!