Like others have said my first inclination is to tell you to up your nic. However, although I have been vaping for over a year, I can tell you it has not been without some cigarettes particularly in high stress situations. For example, the day I had to replace my sewer line I smoked a whole pack that day. Besides doing the work basiclly by myself, renting the backhoe, not knowing what I would find, not knowing how deep the main would be, and on top of all of that my job exploded that morning and was on the phone for almost 2 hours straightening out a situation.
What I'm trying to say is it is not easy to just quit cigarettes and do nothing but vaping unless you've really made your mind up and have some very strong willpower. Do up your nic but hang in there and vaping will get easier. If you have to smoke on occasion don't beat yourself up. But do continue vaping and remember why you wanted to quit cigarettes in the first place. Vaping is very enjoyable and a h*ll of a lot healthier for you. Hang tough, my friend.