good morning Clowder
I had one more thought for KT, it might be worth trying a lower nic level as well. You mentioned a heaving feeling in your chest that leads to anxiety/panic. I was thinking about it, and anxiety turned out for me to be the clue that my nicotine levels were too high. It wasn't something that had happened when i smoked too much, and smoking calmed me, so it took me awhile to realize i reacted a little differently to the nicotine alone without all the other chemicals in the smoke.
you could also try each of the components and work your way
through the possible combinations and see if you can isolate which part you're reacting to. For example, unflavored with 0 nic VG (or VG/PG), then unflavored (or VG/PG) with low nic, flavored without nic, flavored with low nic, etc.