That's a tricky one. Obviously if you ask a dr they will say to quit, but being an ex smoker I know that's harder than it sounds. I've heard before with pregnant women that some drs have said if you only smoke a couple a day then it's more stressful to quit than it is to continue. But my opinion is to quit, you'll feel better if you do. Ask if you can try a patch and see if that helps. Then try finding something to do that will help relax you - crafts, walks, yoga, etc. Plus think of how much money you'll save if you quit! You can do it - just find an alternative, and in no time you'll forget all about smoking.
I smoked for 13 yrs and quit nearly 10 yrs ago. I started smoking in 6th grade! I find myself fortunate that my lungs were clear when I got my first breast cancer.
Good Luck to you!