Hi Emma,
I've had asthma symptons for a long time now - over twelve years ago since moving to a different part of the country which seemed to trigger them off (as well as really bad eye allergies which was infinitely worse since I had to have drops three times a day

).
Anyway . . . I used to blame my asthma for my shortcomings at sport at primary school and used it as an excuse to avoid games lessons at secondary school. But I was just being lazy and mismanaging my asthma. I understand your concerns about being diagnosed as asthmatic - we all have this mental image of some poor person clutching their chest with one had, resting their other hand on their knee, hunched and gasping for air. But it doesn't have to be that way!
A couple of years ago I realised that, having blamed my relatively inactive lifestyle on my asthma for so long, I had become pretty unfit in general. I wanted to lose weight. How? By running (and eating less

). To begin with running was tough and I really had to grit my teeth to get through it because of the wheezing. But that's when I made a concious effort to take my preventative medication religiously - twice a day as instructed. Before then I lazily skipped a day here and there because I didn't suffer symptoms if I remained inactive.
As soon as I got on top of my medication administration I started to wonder if I actually was asthmatic. It was great - I could run like the wind and never really got out of breath. I hope this offers you encouragement. The message is simple: do as your doctor tells you to (including doubling up the dosage if you feel the need, perhaps due to a cold) and you will stay largely on top of your asthma, and not the other way 'round. As you already said, the relief your medication offers you is testament to how effective the condition can be controlled. But make a real effort to stick to the preventers as well as the relievers!
Welcome to the boards
EDIT: If you tell us a little bit more about yourself (e.g. age, typical activity/exercise level, social habits, current asthma medication) then we might be able to offer some tailored advice