I'm going to sound harsh here without meaning to.
I've just had my 3rd miscarriage - I have no kids yet, and I'm grieving for my 3rd lost baby.
Your baby has the chance to be healthy but you are carrying on with smoking and that will harm your beautiful baby. Whatever Penny might say of how her dc's were ok, smoking during pregnancy will harm your baby.
I did every thing I was supposed to do, and still mine didn't survive.
Please please please, for the sake of your unborn child speak to your midwife about the help and support you can get.. It is out there and it will make a huge difference.
Yes it will be hard, And to be honest, the same way I'm going to have to suck it up grieving for my 3rd loss during the week of my first due date, you are going to gave to suck it up (pardon the pun) of getting through the cravings.
If saying this makes me a bitter bitch then so be it. But your baby would be here and healthy, my 3 aren't.
Soapbox rant over