Hi fakeblonde,
I've had asthma all my life. One thing you get used to is that the more stressed you are, the worse it will be.
I might be a bit of a hypochondriac, but I'm sure I can just think about the prospect of an asthma attack (say if I'm going to see friends who have horses, which I'm allergic to) and my breathing gets worse. Sometimes I also feel my heart pounding a bit after my inhaler, but then if you pay attention to it, it seems to get louder and louder.
The best advice I could give would be to try and relax. Stress definitely brings on asthma, or makes it worse. Other, non-medical techniques I find work well are haivng a hot bath or doing a steam inhalation. If you're caught short, a strong black coffee may help (but it might not help your heart racing!).
I'm not saying not to be aware of changes, but try not to think about it too much. Try losing yourself in a really good book for a few hours and see if, when you forget about it, it actually improves.
Once you get the brown inhaler, you should feel better. I barely have to use by blue one at all these days and it is a great improvement. All the best x