Yes, many people have ENS symptoms only in one nostril. Usually - the more resected nostril. Also, compensatory anatomy can reduce the symptoms in the other nostril.
I for instance had total IT reduction in both nostrils, but I have a highly twisted and deviated septum which begins with a very low and frontal septal deflection into the right nostril, right in-front of where the head of my right IT used to be. As a result my ENS on the right is not as bad as the one on the left. Aerodynamics and the impact of form on function in the nose is dramatic and it's very difficult to understand the three dimensional picture unless you have lots of experience in reading CTs (because every picture represents a different two dimensional slice at a different location) and intimate knowledge of nasal anatomy.

I can't tell you if you are irrigating too much or exercising too much. It's up to your own judgement.
The window of opportunity in Kris's case that I mentioned was not about ENS, or her nasal surgery post op period, it was to do with the long term effects of her mucosal reaction to the very serious sinus infection which she just went through. Such an infection may cause permanent damage to the mucosa and there is some window of opportunity following it to increase the chances of that not happening. After all, nasal mucosa with all it's fragility is very robust because it has a highly regenerative potential (being designed to tackle the daily heavy wear and tare of breathing in even the most extreme environments). Please note that that's the mucosa itself, not nasal bones - which are part of the skull bones, like turbinates...