I would go ask for a scan, as others have said the stress is possibly worse for your bubba at the moment.

30 years ago women were allowed to smoke in the delivery room.
yes there are associated risks, but there is probably something that we are all doing now that in 10 years time will be discovered to be sooooo bad.

Smoking is one of the hardest addictions to crack.

One thing thou, what are you going to do if you have the scan and it shows a smaller sized bubba? will it make the next few week worse for you?