Inr Level Seems to Not Want to Come Up

I had heart surgery in August, 2008. I had replacement of my Mitral Valve. I have an artificial valve now. I am 38 now and to say the least-I was petrified! Anyway, I have been on Warfarin/Coumadin since then and at first I only needed a small dose. Unfortunately, after surgery, a few weeks later I picked up smoking again. Slowly, but it is slowly increasing ( the norm). My Coumadin Clinic Advisor has adviced me that according to the foods, etc. that I have eaten, everything else is normal. She believes strongly that it is the increase of my smoking. I Really need to quit for not only this problem, but to remain healthy as well for myself, my children, and my grandchildren. Please help me as my INR is only 1.5 after 3 months and it seems that due to smoking, this may have something in the equation. I worry myself sick over these things. I know I need to quit, i cannot take Chantix, due to a bad experience. Can you shed some light on this and what could be causing it. Please give me some help as to what I need to do and how to do it to get my INR number up. Thank you VERY much for your help. My email is ****** or you could reach me @ *******. Thanks for putting my mind at ease, I have a panic disorder and I tend to worry WAY too much. God Bless!!!! K.