Do you have an asthma action plan? If not it's a really good idea to have one. You can download one from the internet and have your doctor fill it out or you can get one from your doctor and have her fill it out.
It goes by a green/yellow/red zone system and the goal is to stay in the green zone. It's very easy to follow and pretty much tells you what to do and when to do it. I don't have a very good perception of when I'm having problems (i.e. I can't always tell when I'm not breathing right), so I tend to wait too long and cause myself more issues than necessary. Since I've been following my asthma action plan I've been having less problems. It's very preventive, so it can help you catch things early on before they become bigger problems.
Also, you will know when it's time to go to the hospital

I had that problem once, too, and I could tell the on-call doctor at my clinic thought I was a complete idiot when she told me I should be at the ER, not waiting for her to call me back. That's when I learned about asthma action plans.
If your asthma is not under control it's a good idea to record your rescue medication usage and peak flow readings (morning/night and when you have problems) it will help your doctor adjust your controller medication or add one if you currently don't use one. I record my stuff on a MS Excel spreaRABheet and bring it to my doctor appointments. I record my peak flows for morning/night (most of my remaining issues are at night), when I used my rescue medication, why I used it, and any notes.
I hope this helps you. I'm pretty new to the asthma thing myself, but these are the things that have helped me.