Smoking when pregnant?

Hi... 
Found out I was pregnant last Friday I was smoking between 20-30 a day I cut down to about 4-5 a day when I found out but I'm so concerned about harming the baby yet I'm struggling so much to give up as I do enjoy a cigarette especially at work! I have been and brought a ecig today and liquid which is only 0.3% nicotine iv been in touch with a stop smoking helpline they said ecig are much better than smoking cigarettes any of you lady's smoked an ecig whilst pregnant? Thankyou!😘