Sounds like Doc missed a few months of med school, or at least is not educated about nicotine. Nicotine is not a carcinogen. Nicotine gum does contain tobacco, and therefore is also not a carcinogen. The American Cancer Society recognizes nicotine gum as a safe nicotine replacement therapy -
Nicotine Replacement Therapy to Help You Quit Tobacco
But responding more toward your main topic, I have a bit of personal experience to share.
Background - For 10 years I strictly vaped traditional "freebase" e-liquid in popular tanks with coils on common mods. I started with around 16mg nic strength the day I quit smoking in 2014 (was a pack a day for 30 years), and was able to gradually taper down over the course of a year, stepping down to 16mg, 12mg, 6mg, and then finally 3mg. I truly believe that vaping saved my life.
But then the state I lived in banned flavored e-liquid, and eventually by early 2024 I found myself unable to obtain it. Desperately not wanting to risk going back to smoking, I was able to obtain some popular disposables through a friend and began using them instead.
I have to admit - I enjoyed the convenience and certainly did not miss dealing with coils, tanks, messes, batteries, mod tweaks, etc...
BUT, between the convenience and the "salt nic" or "nic salts" liquid that is used in them being so much stronger than traditional e-juice, I personally did encounter some adverse effects. First, it quickly became much more adictive for me, and I found myself hitting the disposables more frequently. Eventually I started to feel some chest tightness, sleep issues, new anxiety, and raised blood pressure. Still, I tolerated it for quite while I could not obtain traditional e-juice in order to go back to my tanks and mods.
So, while I assume that many people don't have the kind of issues that I did with disposables, for me personally they just aren't a good choice and seem worse for my health than old-school vaping.
But as far as what your Doc has to say, such as chain-vaping being "10 times worse than smoking", well... you're talking about the same doctor that thinks nicotine gum causes mouth cancer, right? ;-) I'd get a second opinion on that if I were you.
My last personal take on your sitch - I can definitely understand how much easier disposables make your life, especially since you often live in a truck (I spent a year OTR moving furniture for United Van Lines, living out of a Peterbilt bunk and truck stops back in the late 80's), I'd still encourage you to try going back to at least semi-non-disposable vaping. There will likely be a certain amount of withdrawal symptoms because you'd be stepping down from crazy-high salt nic to a lower / mellower freebase nic, but you'll survive. Not long ago I switched back from disposables with nic salts back to traditional 3mg nic freebase (because thankfully I found a friend who is able to help me obtain flavored e-juice again), and I did experience some discomfort for about 10-12 days while adjusting to the strength change. OR... Something else that might be a good option for you - switching from disposables to pod mods (like XROS or Caliburn or OXVA etc...) and fill them with your favorite flavors of nic salts juice. That way you'd have the high level of nic that you've now become used to from the disposables, but in a somewhat smilar device that you have control over and could use to work toward switching back to traditional freebase juice. I'm actually in the process of switching from tank mods to pod mods myself, because I'm no longer a "cloud chaser" and I want the ease & convenience of the disposable pod devices.
All of that is just my personal experience and opinion (except for the nicotine not causing cancer part - that is a medical fact), YMMV.
Sorry it's gonna be such a long week for you.
