In many cases correcting a deviated septum can correct asymmetric nostrils but not always. It would require an actual examination to be sure, but if the end of the septum is pushing off to one side, that can be the culprit. I would make sure you see a doctor with both septoplasty and rhinoplasty experience. Good Luck!
One of my Nostrils is Crooked. Will Septoplasty Fix That?
Doctor Answers 3
Most crooked noses are caused by a deviated septum
However, a septoplasty doesn't always straighten a crooked nose. When we refer to a deviated septum repair, its the internal portion where the maximal airflow is. The external portion or bottom of the nose as in your case, doesn't necessarily get fixed with a septoplasty alone.
In the photo you uploaded, the bottom of the septum is crooked as well as the portion between the nostrils called the columella. This can often be fixed along with a septoplasty but might take a few more steps. As for crooked nostrils, once the nose and columella are straightened you would see that the nostrils become more symmetric as well.
Correcting crooked nostrils
Asymmetric nostrils are often (but not always) caused by a deviation of the septum in that area. Surgery can be used to correct the problem, though it may involve more than your typical septoplasty to adequately address the issue.
Check out my web reference link below to learn more about crooked nostril repair: