In addition to the chemical changes from quitting, it's worth considering that as smokers we learned to use cigs as our method of coping -- especially those of us that started smoking as teens, before we really learned healthy coping skills. Any time that we felt stressed, tired, down, over-excited, or just about anything, we lit up and that was that. I think that's a big reason that we can get 'cravings' for so long after quitting; even if the chemicals in cigs caused brain changes directly, a large part of that was because of our behavior and the ways that we changed our brain ourselves to accommodate and extend them. It's really important to learn new, healthier coping skills, and preferably to dis-associate these feelings with a chemical fix.
If you feel like you are missing something that you needed from smoking, I'd urge you to talk to your doctor. If you've already been medicating with probably the most risky thing you could, and were able to live with some of the worst side-effects you could get, then you'd definitely have what it takes to do it the right wayYou still need to learn the behavioral stuff to make it work, but they have spent huge amounts of their adult life seeing what does and doesn't work (for what people and in what circumstances)
Consider, though, that there have been a lot of people (with no intention of quitting smoking) that took Welbutrin and suddenly felt like they didn't want to smoke; obviously they found (even accidentally) that some of the meds completely satisfied the desire for the chemicals in tobacco, and in a way that gave them better control of their life.
It's also worth eating some extra fruit and veg when quitting. Smoking may have caused some deficiency or another, and you'll need all the nutrients you can get to help healing regardless.
I'm not a psychiatrist, but this stuff is covered in the smoking cessation material, and it was pretty evident in my experience. Now that this stuff is settling out, though, I'm feeling better and more even-keeled than I ever did when smoking.
I agree with this also.... this is the nature dependency , sub consciously most drug addicts are entirely terrified of living without whatever substance it is they are dependent , that fear can far outlast the half life of the drug .... smoking is particularly pernicous as nicotine needs to be administered so often ... Imagine if you smoke 20 cigarettes a day for 20 years , that's 146 000 cigarettes .... there aren't many things in life that you do that many times .... Imagine you take one dump a day and you are 35 that's 12775 dumps in your lifetime a small fraction of the amount of cigarettes you have smoked