Ive had asthma all my life. I used to have to use this archaic looking machine when I was little everyday, it was bad.
So no I cycle and do century rides and more regularly. At first asthma was an issue and I used albutural (sp?) (which is the same as your ventolin) which is basically a fast acting lung-tube opener so I can suck down more air.
However, upon asking my doc about it he got me on a preventative called,Flovent HFA. It comes in a yellow/orange puffer container. I use it once in the morning and once at night.
Since using Flovent, I no longer need to use albutural. In fact, for the last couple of months I have really slacked off on even the preventative, Flovent.
Before getting onto Flovent, my asthma, like you, was getting worse and my instant puffer reliever albutural seemed to be having less and less of an effect.
Maybe you can try a preventative like I do? Worked for me! I don't even carry albutural puffer anymore. Less weight