I'm not sure what you are trying to say, so I guess it isn't very natural! Do you mean 'You could have misheard your teachers in previous lessons'?

Definitely not natural. "Should have" is for past advice or unfulfilled expectations, neither of which make sense in this case. I believe that you mean to say "You must have misheard your teachers..." "Must have" is for conclusions about past events based on some evidence. We have evidence in the present that you misheard your teachers in the past, but we are not 100% certain that you did. For example, "You heard your teachers say that 'I am loving cake' is correct? No, that can't be right. You must have misheard your teachers in the past."

I feel it should be like "You would not have heard your teachers properly while you were taking lessons in the previous class."

You can say "you might have" or "you must have".