I would go crazy trying to remember which bottle to add to which device and how high I could crank the watts. lol. I do not think nic is my problem. I am pretty convinced it is VG. when I first wake up in the morning the coughing is minimal. As the day wears on and I have vaped it gets worse. By nighttime it is bad.
Could it be PG that you are allergic to? I recall some people on the forum, including Anna, reported being allergic to PG. She would use PEG instead. I think it was PEG-400. You might get a little bit of that and try it.