Hi. I can imagine you are finding it hard.
Historical testimony shows that many people needed to transition with some dual use of tobacco and vaping for a while to eventually quit smoking.
You haven't told us the power you are vaping at, but I will assume it's not 'low' in the old standards of 4-8 watts. People did quit at that power, some with as much as 36mg but over 1, 2, 3+ months, maybe even years.
12mg in a modern device should be plenty enough nicotine. I suspect that is not where your problem is.
Don't give yourself a hard time, smoke a little, vape a little and try to send the direction towards vaping.
Many of us used 24mg. I would think you'll only give yourself a headache if you think you can kill the cigarette cravings with higher strength juice.