Good luck, it is very hard and I wish you success. I have been an on off smoker for about 10 years. I gave up when preg with DD and stayed off for a year after (breastfeeding). I gave up this time about 5 weeks before TTC. I am lucky because I only ever had 5 max per day.
I had two friends that continued right through pregnancy and all their 3 babies were fine. I am not condoning, but if you couldn't give up at least you know there are others out there. Of course, giving up is the ideal. Once you do give up, you tend to wonder how and why you ever smoked. I do not plan on ever smoking again. GOOD LUCK xoxoxo