When I first started, I needed to go to 24mg juice to keep the panic away, was vaping constantly. I was buying and using 3 to 4 -30ml bottles of it every month, which would give me a consumption of 3-4 milligrams a day. But after the second month, after initial withdrawal was diminishing, I started being more aware of my nicotine intake, so started decreasing the mg nicotine, by 25% ~ I did that twice, now down to 6 or 12 mg juice, with no panic, no further withdrawal. I began DIY so I could keep cutting down, and in the process also dropped juice consumption to 1½-2ml per day!! I feel like I'm still vaping heavily, but am now after about 19 months, I have to go look for my PV once in awhile! That never happened to me when I was smoking, I never lost track of them. In fact, I was smoking more and more, and killing myself in the process. Panic was the factor I couldn't deal with alone.
So the main thing I think is to be open to reducing nic density, and just let the vaping cadence play itself out, don't set goals that will endanger the "comfort" zone you're building and expanding every day by vaping. The panic factor can definitely rear it's head again if you do that. Then we find ourselves back-sliding a bit.
That's the biggest trouble with conventional 'stop smoking' efforts. That just exacerbates and emphasizes the discomfort zones. Expecially if "conventional" means using someone else's "guidelines".
It is an extemely personal phenomenon to find your sweet spot, make sure it's not a challenge to your goal, instead of just accepting your vaping as a place where you are at the moment. There are days when stress plays a role in how much you rely on your PV, but there is always going to be stress. Your way of dealing with it will change now, as there is life after smoking, and life will continue to be something we have to 'grow' into!
With vaping, I'm not quite ready to stop yet, but "life" is becoming so much better I know now I can deal with stress much much easier than I ever have. My comfort zone has grown, my panic zone dispersed into it !! I also have lived with ADD all my life, to me this "comfort" thing is BIG. I smoked for 44 years, 2-3 or more PAD. That's how big this is!
[edit] And by the way, my plasma level of nicotine is at about a level of 100 ng/l, down from about 4000 + ng/l before I started vaping. I can live with that. Literally.