Nose surgery - breathing problems
What you really need is a examination of the inside of your nose by an experienced plastic surgeon or ENT. The nostril size is unlikely to be contributing to the inability to breath through the left nostril. You may have a deviated nasal septum or enlarged turbinates that are contributing to the feeling. Best Wishes!!
Thank you for your question. A deviated septum occurs when the partition that divides the nose into two nostrils is crooked and obstructs nasal breathing. The good news is that your nostrils can be treated with surgery. I suggest that you consult with a board certified facial plastic surgeon about a Rhinoplasty procedure.