I'm going to jump in here with my own WAG, as the OP said she was getting enough nic with the lowest level patches and gum, so she may be sensitive to the nic levels. A lower level may help...
I smoked 1 1/2 PAD full flavor, and needed 36mg juice to beat the cravings, no headaches, no problems....
BUT when I had tried patches I used the highest levels, and would still pull it off, smoke a cig and slap it back on. Gum I could chew through a 1/2 pack in no time, at the highest level.
If you're sensitive enough to the nicotine in the lowest levels of patches and gum, you sound to be the exact opposite of me. Vaping at 6mg or 12mg may be the level you need, each person is different. There's no magic level to fit someone "because I used to smoke....", only a guesstimate starting level to adjust up or down depending on how you feel.