Quitting

On May 18th I quit smoking. Then around the 20th of August I was totally stressed and smoked for 3 days. Since then I have smoked 3 times. It is now September 27th and I am wondering if Im going to be able to stay off those nasty little buggers.
I feel like if I start back maybe I will stop eating so much and will stop gaining weight. Is that just a mental thing or do people really gain weight because they are just so use to that hand to mouth motion that instead of putting a cigarette up to their mouth they grab a snack.
If they didnt smell so bad and kill you I dont think I would ever quit. However, now that I do not live with a smoker it seems much nicer not having my clothes or hair smell so bad. That alone should be enough to keep me from wanting to smoke right?
Any suggestions will be greatly appreciated here!