I did not have this reaction in the first few weeks, but my quit pattern was different than yours. Currently, I am keeping the crave diary, and I am finding that the overall trend is less cravings as time goes on. There are occasional "spikes" (higher cravings on particular days), but those are lower each time, too. If you aren't already using this tool, I suggest that you do. You will notice your own patterns, and this helps with self management.
As for you having more intense cravings as you move forward to day 12, I do have a theory. This may or may not be correct, so you can take it for what it's worth. First, as you know, this is not physical, since the nicotine is out of your system. For whatever reason, you slipped up on Day 12, so that has become a focal point for you. Whatever psychological barriers you have to quitting are being focused around the approach of day 12. Perhaps there is a sense of "if I can make it past Day 12, I have really quit," and this raises all the anxieties that go with the idea of finally quitting.
I know the concept of the "last cigarette ever" was a very hard one for me to wrap my mind around and accept. That's why I took so long to even get to that point, and I am still somewhat in denial about it. I try not to think about it too much.
Some things that have been helpful for me on high-crave days are to: 1) Remind myself that it's just today I need to get through without smoking. Tomorrow will take care of itself if I just focus on today. 2) Go to bed if today seems to long. (The internal battle can be exhausting, and being tired lowers willpower even further.) 3) Look at the quit meter. Think about the money. Think about the days of life gained. Think about how much better I'm feeling without smoke in my lungs. Think about earning a little bit more of that each day.
Well, hopefully, there was something in these ramblings that was helpful. Hang in there, my friend.
And one day at a Time.....
