You know I fretted over this too. My family and doctor were only happy for short time with me quiting now they keep asking me when I am going to 0 and quiting vaping. I was and still proud I maded it this far for over four months. But I did work myself from 24mg to 18 then 12 but I started getting the thoughts of smoking again so now I just stopped freting and have the 18 as my all day vape and my second strings of juices are 12 so when I feel I vaped to much I just switch over to the 12 and be done with trying to buck the system in going any lower for now.
There is a time and place to listen to your doctor and family, this isn't one of them, lol. Congratulations on quitting and cut down slowly. Do what works for you.

as ok as I ever am 
I actually still have some of the 16mg that when I need a kick, maybe a stress day I add it to my tank that normally has a zero in it so I guess it's working!

