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It sounds like you trust your teacher, which is very good and quite rare. Honestly, it sounds like he is giving you advice that is straight forward. Take it at face value. He clearly thinks you are doing well and making steps forward, but at this time you might not be ready to audition. It just takes time and a level of readiness.

As for being a graphic designer on the side, I can understand how it might be hard to not see physical evidence of your work, but you get used to it. I don't know much more to suggest to you. I'm sorry. But over time you do grow to trust people's opinion and suggestions, while still not giving their voice absolute power over you.