I know you said that the PV is performing well, but try and blow out the atty anyway. Maybe run some hot water through it and dry it... or just try a different, new, atty. It does make a difference on nic vaporization and absorption. After 8 days, the atty is starting to gunk.
Also, I hear that heat and sunlight (most parts of the US have little of either this time of year) can reduce/destroy nicotine levels in juice. I doubt that's the issue, but I mention it. Watch out for the 36 mg. Some people need it... most don't. Nicotine is a vasoconstrictor.
2 cents. Good luck!