Meggles,
Lots of information and yes, the others that have posted prior to me have taught me a LOT. PG/VG and nic does matter... AND making sure you have whatever atomizer you are using wet. Dry can make you cough.
On another note, this is what I have come to find out.. (For you this point may be mute but someone else may find it helpful)
The longer you have smoked, you seem to cough more or take a little more time transitioning, but it only lasts a few days to a week at most. The younger crowd seems to be able to take a large puff and have no problems. I have COPD, and for me it was small puffs at first, and the more I moved away from the analogues, the easier the draw became.
Another factor is anyone that has Acid Reflux, or tummy troubles seem to have a tough time too? Not sure why? Something to do with the esophagus, would seem likely?
So if changing your PG/VG or nic doesn't seem to do it, hang in there, it will lesson. I still cough but from my COPD not from the vape. My lungs are wayyyy better then they have been in a long time!!
Good luck... cheering for you!