Good luck. I've never had to deal with this, my parents both smoked when we were growing up, and none of the 7 children picked up the habit. (just lucky, I guess) My children finally guilted my parents into quitting, bringing up the fact that they would miss all their milestones if they kept on smoking.
You need to find something to do with your hands, along with the gum. Maybe sunflower seeds? Try not to just go to candy, that can pack on the pounds. Don't stress about the weight gain, you can lose the pounds, you don't want to lose your lungs!
I've tried the seeds before, I chewed so many that I got salt sores or something inside my mouth. maybe I should've gone to unslated but those taste terrible. Now I've gone to sugarfree orbit regular gum when the nicorette isn't shoved up into my mouth.
You can do it. I quit chewing ( pack a day ) last year when my 8 year old ask me to quit so I wouldn't lose my jaw like the man in nursing home. I quit that day and have not had a problem.
I have noticed I don't get headaches as often and my teeth are whiter and better breath.
Stay with it. Everyday is one more away from it.