Oh, don't I know it! I still haven't managed to quit cigarettes completely. I have stopped buying them, and that goes a toward a great deal, but I live with people that smoke and my DF smokes so sometimes it's hard not to ask someone for one or two. I never managed to quit with my DS and he was a very small baby and I've always felt super guilty about it. He has certainly caught up by now and I don't think he has any lingering issues over it, but man, I felt like a terrible mother when he came out at only 5 lbs.
It's very hard to quit smoking cigarettes when you've smoked since you were 14. I am trying my very best, though.
In the end it was the unbelievable, insatiable feeling of wanting a cigarette that made me quit. I couldn't believe that something could have that much of a hold on me. It made me ANGRY!!! I got pissed off at cigarettes and never went back. LOL. So have pity on yourself mama. It's the cigarettes. They're made to be that addictive. Pity yourself, get angry at the cigs and the companies!!!
For DH it was a lot harder, and he does still have the occassional social cigarette ubt our son doesn't see it, or even smell it or anything so I just look the other way (mostly).
It also doesn't help that you live with smokers. That makes it a billion times harder.