Hi navigator! Sorry to hear you're having so much trouble with your asthma; it's a real pain in the ...., I know personally. As a matter of fact, I have adult-onset asthma; it was diagnosed just about 30 yrs ago, after I'd already been a smoker for nearly 10 yrs. Naturally I didn't quit.
Thru the years I tried several times to quit smoking, but it just never worked for me, so I'd go back to smoking, going to "Lights," then "Ultra-lights," just so I could keep smoking without coughing up a lung with every puff. Over the last 10 yrs or so, with smoking only a pk a day, my asthma was very well-controlled; I used no medication except a rescue inhaler, because the potential side-effects from all the maintenance-type drugs are just so horrible.
Last winter I got interested in e-cigs, because it was just so blasted cold outside, I didn't wanna go out there anymore, just to smoke. I came here, got an eRoll (cigalike), found an ejuice I really liked because it tasted just like my cigarettes (virginia slims ultra-lights) but with even better throat hit than the cigarettes -- I managed to quit completely after about a month of gradually phasing out smoking and phasing-in vaping, because the more I vaped, the worse the cigarettes tasted. And at first, vaping that "Virginia" (from MyFreedomSmokes, their high-PG (85%) blend), my asthma improved dramatically -- after just 5 days smoke-free, I no longer sounded like a water pipe when I woke up, and didn't start grabbing for the inhaler before my eyes were even open -- it got MUCH better.
Over the summer, I developed appendicitis, got the wretched thing taken out, suffered godawful sickness afterward, and ended up going back to smoking for about a month, while doing the same phasing out/phasing in thing -- and managed to get smoke-free again -- but 10 days later, those godawful cravings I had after the surgery came back -- so I added WTA, the cravings went away, and I thought OK!
But, I was losing my taste for that Virginia tobacco flavor; I found another juice I liked a lot, Blueberry Muffin, and started vaping it; unfortunately, the one I was vaping was 50/50 PG/VG, and I knew already that that was too much VG for me; anything more than about 25% VG just closes off my lungs completely. So I found another, at sweet-vapes.com, and they let you customize your PG/VG -- I'm getting 80 or 90 percent PG. I also mix it with some Banana Nut Bread, which I DIY at 90% PG -- but I still add WTA, so that it makes up 10% of my ejuice -- but now, my asthma is completely out of control. Since I'm not vaping much VG, I know it must be something in the flavoring that's causing the problem. One thing I've done recently is increase my nic level and the WTA, so that I don't need to vape so often -- at first I needed to chain-vape, to control the cigarette cravings, but now I don't really feel the cravings anymore, so vaping less is a much better deal for my lungs. But, the asthma is still not controlled.
Tomorrow I have an appt with my asthma doc, and this time I plan to ask for some maintenance medication, because I have to get back in control of the asthma -- at this point I am NOT ABOUT to go back to cigarettes, because a) they cost a lot more than vaping; b) they give me lots of yucky crap to cough up out of my lungs; c) they stink and my husband likes me better NOT stinking; and last but certainly not least, d) cigarettes will eventually kill me as they killed my father, with lung cancer, and it's a horrible way to die, attached to a respirator in the ICU.
I definitely suggest high-PG -- 80% or more; and though it might be necessary at first to vape a lot, meaning you need a low enough nic level so you don't get nic sick, the highest level you can tolerate would be better, to keep from vaping quite so much.
If you can tolerate tobacco-type vapes, they're probably better than the sweet ones; they don't have so much flavoring, which I'm finding is definitely a problem -- that's why I'm starting to learn to how to DIY my own ejuice, so I can be in control of WHAT is in my ejuice, and how much flavoring is in there. Myfreedomsmokes.com has a number of different tobacco flavored vapes; their Virginia, as i said, tastes remarkably like Virginia Slims cigarettes, so their other 'taste-alikes' are probably good too -- they're great folks, have a great reputation, and really know what they're doing, with tobacco vapes -- don't get the VG version, because that stuff is so thick, it'll glue your airways closed.
And talk to your doctor -- if you're not taking maintenance meds for the asthma, maybe you should be; my doc always tried to push them on me, but when I was in control of the asthma, I didn't need them -- now apparently I do, at least for now -- I have 39 yrs of smoking damage to heal!
And last but not least, don't beat yourself up if you can't drop the smokes like a hot potato -- I didn't, either time; it took a full month both times I quit, to be totally smoke-free -- if vaping can help you cut down at all, that's a win, and a step in the right direction -- be patient with yourself. It's a big problem to overcome, but it CAN BE -- if you really want to.
Andria
So, since I took that bedtime dose at midnight, I'll take another dose at noon; I should be able to get my rescue inhaler usage down from the way-too-much 10-12 puffs a day to about 5-6, very easily! 
