I think you're okay. If you were a heavy smoker(pack or more a day) keep in mind, you were getting a whole lot more than 18mg a day in nicotine. Just a thought. Of course if you're that worried try some lower 8, 12mg nicotine and just use the higher mg when you're having a fit and trying your best to stay away from the stinkies.
You can also, in an empty bottle cut the juice you're using. A gallon of distilled water is 1$ some, Humco USP grade vegetable glycerin is found in the pharmacy section(walmart) for about 3$. In an empty bottle fill it half way with the juice you're using(maybe a 6-10ml sample bottle) then add 4-5 drops distilled water, and VG almost to the top. Shake. If too thick, add more distilled water. This may cut on the flavor, however for a "between a hard place and a rock" until lower mg juice comes in the mail, if you're that worried, it's an option and your mg will then be at about 9mg.
+1 Water, some food, food with fiber will keep it moving-oatmeal, raisins, blueberries, avocado, most seeds + much more.