That being said, at high levels, nicotine can speed up your heart rate, make you dizzy, and make you nauseous.
Got real sick to my stomach once from pure organic tobacco. I met with someone at The Cherokees of Georgia Pow Wow, hosted in the Cherokee behalf by the Sioux Nation and they had the tobacco. It would not have made me sick had I exercised moderation. instead, being young I
had to wad up about three full leaves of barely cured tobacco and gnaw on the quid.
I did not need any tobacco, or nicotine for about two weeks. even being around where it was at made me rush to the head. The first three days was spent over the commode parsing back a decade of junk food. After that, I was alright or so I thought. It was then the backdoor trots caught up.
Currently, I use 18mg/ml nicotine for vaping. Got a higher tolerance I find. As you point out though, the nicotine does not cause a
buzz or high particularly. For me it does help settle anxiousness a bit and anything which helps that for me is warranted. I also have high blood pressure but it is under control with exercise, diet, medication, as it
has to be now lest I face another stroke. Had a mild one, unaware of it at the time, few years later a doctor confirmed that it was indeed a stroke albeit mild.
For the OP, I would advise against raising nicotine level. Try instead to get some better gear. Once you find gear that functions well enough, lower nicotine rates can do the exact same as higher rates. Except, lower rates are for sure a safer value if you're doing risk assessment. I would do lower if my body would allow for it, and yes, i have tried doing lower. For myself lower doesn't preform as exact as the higher rate. it is indeed subjective for each of us. Rather though aim for lower nicotine.
This comes from roughly 35-40 years experiencing tobacco. It's not something I would actively encourage for others.