I'm also between 3 to 5 ml a day, (at 12mg nic,) maybe more. It's tough to gauge when you have 5 tanks in rotation, and I hit them all.
I do see I have to be a bit careful. With analogs, you get the feedback that you had enough, the ashtray is filled, the pack is emptying, and you are really taking your fourth break this morning to step outside???
But with vaping, you don't get that sense. And it's not good when you overvape. My voice gets scratchy and I cough in the morning after a night, a coupla hours of TV or websurfin, where I can drain a 2.4ml Triton tank. I have to remind myself to PUT IT DOWN!
The other night was about 6° F, with wind and snow. I smiled, and thankfully exhaled a plume of vapor that I don't smoke no more.