I use max VG, as I'm sensitive to inhaled PG, but really everyone's different. You may not want to go *too low* VG on a sub0hm device as the vape tends to get a bit anemic below 50%, though if you decide on a MTL setup, which I'd probably advise given your juice consumption (even if you chain-vape a MTL device, you won't go through so much juice and that will help) that ratio is more open for a debate. A higher throat hit (menthol, or high PG juices) may "remind" you of a cigarette more, and you'll get more satisfaction.
It is really rare for me to recommend adding nicotine, and if you do I'd suggest a small amount, given the volume that you're vaping and your cigarette habits, but you may as well inhale through a straw to get "nic satisfaction" from the hand-to-mouth action of a cigarette than a 0-nic e-juice setup, and I believe you are chain-vaping so much because you are NEEDING that nic satisfaction, hoping for it, and not getting it. Even if you were to make your nic juice 3--6 m.g. in a MTL device, you'd at least have a *chance* of getting what you are looking for.
TBH, I wouldn't have taken up vaping to quit for the inhalation effect alone-- I can get that via deep breathing, honestly. Nicotine itself is far less harmful than cigarettes, and the nice thing about an e-cig is it's much more customizable. I'd try at a low nic percentage, if that's not doing it for you, go a bit higher, and then work out a TAPER plan for yourself, even if it's a rapid taper, but give yourself a month or two to get over detoxing from all the chemicals from cigarettes BESIDES nicotine, first. Vaping nic does NOT have to be a forever thing for everyone, though some folks prefer some nic in their juice in an ongoing way.
But the mere AMOUNT of vaping you are doing to try and "feel like a cigarette" tells me you are trying to "get" something that you won't "get" with 0 nic juice, and I'm not sure the amount you are vaping would be any healthier for you than adding in a small bit of nic to a MTL device. I'd really be worried if I was consuming that much juice....
Anna