Although I am not a medical professional, I am on many of the same medications as you are. Advair and singulair are what are called "controller" or "maintenance" medicines. You have to take them every day even when you're feeling well in order for them to work. If you stop taking them, or don't take them as directed (called being "non-compliant" with your medication), they won't work as well, if at all, and your asthma could become bad again. In other words, that you find you don't have asthma symptoms very often means that your medicine is working.

If you think you might be able to go to less medicine, you should speak to your doctor about "stepping down" to a lower dose (probably Advair 125 + singulair, or Advair 250 on its own), but this should always be done on the advice, and under close supervision of, a doctor because your asthma might become uncontrolled again if you do step down (this has happened to me every time I try to step down from my current regime, which suggests that it's a good regime for me to be on - just enough medicine to keep me functioning well, but not so much that I'm taking more than I need to stay healthy).