*Assuming* that you vape about as frequently as you smoked (e.g., 10-minutes of vaping 5 to 8 times a day), "low"* nicotine level should be just fine for you.
* "Low" is defined differently by different suppliers. For eample, I just received some e-liquid from Ruyan Direct. It's 11 mg (I knew that when I placed the order).
As for that assumption, many vapers (including yours truly) vape much more frequently than they smoked analogs (because vaping is so *enjoyable*). If you find yourself doing that, then you may want to cut that 6 mg with 0 mg OR alternate (as I do): vape 0 mg (very satisfying with some of the candy flavors) and the nicotine vape breaks whenever you "feel like a cigarette."
Savor and have responsible fun with the vaping experience!