Is it really asthma?

Hi everyone. I was diagnosed with asthma following a bout of whooping cough as a baby. In and out of hospital a lot as a child. Grew out of it at the age of 11, but it came back following a bereavement when I was in my 30's. I'm 62 now, and on Symbicort (which gives me horrendous leg and foot cramps every night). I've been put on several different inhalers at times, had various tests, tried a nebuliser etc, but nothing improves my peak flow. It remains around 250, even after Ventolin. Luckily I am attack-free and my life is not affected by the asthma. But is it really asthma I have???? Could whooping cough cause it? I am not allergic to dust, but I do sometimes feel a tightness with strong chemical smells. Why do the inhalers not improve my peak flow??? (I am using them right, and have tried a spacer).

Hoping someone can advise. I know I'm luckier than so many of you out there. Thanks.