Long story short, it was pointed out by someone else that you can't change Narc anymore after the entire quest line is done. As in she can no longer deflate and whatever state you had her in (besides having filled breasts) is now permanent. When you talk to her after everything is done, you can't swap out of the chat options from after the quest is done. I've tested it by going up to 5 days after the quest is done and there is no change.
