I know how you feel. I got into something a few years back and it had me messed up for several weeks, and a few weeks ago I had it really bad for like 4 days where it was like what you describe you have now and I could only take like a quarter breath. Supposedly caffeine is good for helping people with asthma breathe better, and I don't know if they still do this now or not, but when I was little, I had a nebulizer and it always seemed to do the best job of making it so I could breathe again for a while. Better than any puffer. The downside is it's not nearly as convenient as a puffer, it takes like 30-45 minutes or so, and they used to make a lot of noise, but if puffers aren't working, you may need a nebulizer. This may not work for you, but if you do get straightened out again, something that seems to help me stay symptom-free is singing. It's like it exercises my lungs and helps work free some of the crap that may have already built up in there. Have you been able to figure out any things that may trigger your asthma? I know mine'll be set off from dust, smoke, cut grass, changing of the seasons, exercise, and traveling.
It's kind of funny you said your doctor didn't take you seriously, because the first time it happened to me and I ended up in the emergency room, the doctor was so instant that I had asthma and that my parents had to have already known and were lying to them about it for some reason.