I too have a problem with the "blow more air advice" It's not the amount of air we use, it's how we use it. It's not the quanity, it's the quality. make sure that when you breathe in that the air fills up from the bottom of the lungs. Now this is how we normally breathe so it's not a different skill that we have to learn. But for some reason when we try and play a wind insrument some players will start taking shallow breaths. Doesn't work.
Before we go any further why is your director telling you to blow more air? What do they want you to change?