I'm so sorry, I didn't notice this question.
Asthma can't be caused by stress, but stress and tension can make existing asthma much worse. Perhaps you had a mild asthma all along and didn't notice it - if you've always been slightly out of breath, it just seems normal to you!
However, Ventolin is very effective against asthma, IF you're using it correctly. As I said in my article - you MUST wait a minute or two before taking the second puff, to give the first dose time to take effect. Think of the first puff as a "primer", it's the second puff that does the real work.
I've added a video to the article explaining correct technique for the Ventolin inhaler - please watch it and make sure you're doing it right.
If you're doing everything right and Ventolin is having no impact on your wheezing attack, it's highly unlikely you have asthma. It must be something else.