With smoking that much- grab some 36 to kill the tougher cravings at least. When I find a juice I like I get a bottle of 36, and a bottle of 0 nic- and then mix it.
You can sorta do that math, but analogs have things in them to ensure that you get as much nicotine as fast as possible. Things like ammonia to paralyze the cillia so the smoke gets in easier (and does more damage)- and the list goes on from there.
Without all of the extra chemicals it's a slightly different biological process, and one that takes some adjustment.
Some days I need a lot of caffeine- some days I don't...same with nic. You're already an addict- focus on getting off analogs, and do whatever it takes to do that, and then worry about dropping your levels. It takes time- don't rush it, or beat yourself up over it.
Quitting with ecigs should be a pleasant experience- don't suffer needlessly with low nic juice.
PS- I counted, and for me, an analog is 20 drags. I smoked 100's.