As everyone else is saying, you need to up the nic strength to match your old nicotine level. I started vaping out of curiousity, and started out on 24mg cartridges. Two days later I had no desire for normal smokes and havent looked back since (2 months). My first juice purchase was medium strength, 18 I think, and I found myself wanting to vape constantly and was very moody and irritable. Went back to the high strength carts and all was well. im 38 and smoked a pack a day since 16. Think its better to high nic to get you over the hurdle, then kick back the strength as you see fit. In my personal experience, after 5 weeks medium strength did the trick and my next purchase will be low nic. Good luck, hope you make it through this. BTW, I started out with a Luci e-cig, but quickly moved to a 510 with manual switch, to satisfy my desire for the throat hit I was getting with analogs.