A lot of folks find that when they're quitting cigs and starting to vape, that they vape A LOT. Like non-stop.
And the fact is, most of us think THAT'S OK. If it gets you off cigarettes - a little nicotine is not especially harmful, compared to all the crap you are NOT combusting and inhaling.
If you get too much nicotine, you'll feel queasy, or dizzy, or both (sounds fun, right?).
But on the other hand, you SHOULD know the nicotine level you are vaping.
I started on 24 mg nic, which is considered quite strong, but I didn't care, and I stopped smoking with no trouble. Heck, I wasn't even planning on quitting cigs, I just didn't like them anymore once I got a decent vape. That's a little unusual.
I only later cut back the nic, just to see what would happen.
Nothing happened.
Good luck, hope you're enjoying it, and as I said - it's not unusual to vape quite a bit...
Oh - it also depends on the equipment you are using!
Many people start with 18 mg nic in things like a clearomizer, but 18 mg would be a pretty strong hit in a "dripper" or another low-ohms device. Those just seem to deliver more of a "hit" - both in terms of flavor and nicotine.