Get a plain CT PNS (Para Nasal Sinus) done on a Multi-Slice CT Scan Machine. A posterior bony DNS usually gets overlooked in initial septal deviation surgery. Rule out any complications and under-corrections on this CT Scan.

In the normal 'Nasal Cycle', alternate nostrils open and close between 2 to 7 hours. If your right side is normal, you will breath easy when it is open and when it closes down, both nostrils will feel blocked.

If you use nasal decongestant drops regularly more than two to three weeks, you will develop Rhinitis Medicamentosa. Initially the spray's effects lasts 8 to 10 hours and then, as your nose lining gets addicted to the spray, the effect lasts only for a couple of hours.  

the nose blockage is not due to a physical hindrance, rather it is a functional disorder. You should not worry about it. Engage yourself in a regular exercise and warm yourself. It shall relieve your symptoms.