Smoking is a poorly understood addiction. I have done a lot of reading over the years, and have come to some conclusions. Whether these help you or not, it may be useful to revisit many of your assumptions.
While smoking is notoriously addictive (possibly more-so than any other “drug”), nicotine itself is not particularly addictive. If you were to drop nicotine into your coffee every morning, you would be much more addicted to the caffeine, than the nicotine.
What makes nicotine so addictive, when used via cigarettes (or, to a lesser degree, dip, cigars, or pipes), is that you are essentially free-basing nicotine. This is because of other chemicals in tobacco (MAOIs), and also because of chemicals added during the curing process (ammonia, in particular).
Blood nicotine levels aren’t particularly relevant, as a result (and also explains why nicotine gum/patch have such a poor track record). When you smoke a cigarette, the nicotine is delivered to the brain quickly and disproportionately (ie — more nicotine ends up in your brain, and it ends up there almost immediately).
Freebasing anything would make it addictive, but even more-so with nicotine, for two reasons. First, the brain has nicotine receptors (why they exist is a bit of a mystery, but probably has to do with differences in diet somewhere back in our evolutionary past).
Second, nicotine has a number of very positive mental benefits. It calms when you are stressed, energizes when tires, increases concentration when thinking, increases feeling of happiness, and lessens negative emotions. Taken in “ordinary” means (via diet, orally, or through something like the patch or e-cigs), these effects are subtle.
Free-based, however, these effects are very strong. This leads to part of the addiction.
The other aspect of the addiction lies in the role of taste and smell. These senses are very powerful in terms of recalling past emotions (you can smell a tree from your childhood, and the memories will come flooding back). Well, the taste and smell of cigarettes triggers recall of all of the powerful effects nicotine has had over the years. If you are concentrating, for example, the thought of the smell/taste of cigarettes will bring back (subconsciously) all of the times that “free-based” nicotine made you concentrate so much better. If you are feeling euphoric, this taste/smell will bring back all of those times it made you feel even better. These “cravings” are all the more powerful because we are recalling back when we free-based this chemical which has so many positive effects.
The bottom line is that smoking is not an ordinary addiction, nor is the habit “just a habit.” It has very strong roots in your brains chemistry, and there are many different angles to it.
Personally, I quit via the e-cig. It rewires the taste/smell connection. But it does so without the other chemicals which create this free-basing effect (and also with the carcinogens). But for me, knowing why I still occasionally crave, and will always occasionally crave, a cigarette has helped me overcome those cravings, on the rare occasion where they occur.
Whichever route you choose, I suggest you throw away a lot of the conventional wisdom about smoking, and addiction to smoking, because so much of it is wrong. If your assumptions are wrong, it makes success that much more difficult.
When I quit those few times, I actually got depressed....like I lost my bff or a family member, or a limb.
I even cried over the “loss”. I think I may try NA. Perhaps they can give me some coping skills.