You can do it. You already did it. What are you waiting for? Another layer of approval? Another bureaucratic step in the process?
You make decisions. That was basically the point of your education, to teach you how to make decisions. Yes, you have the authority to make the decision. You don't have to consult someone else every time. That other person is busy and preoccupied. Do you really want to hold up the project while you wait for affirmation that you could work harder?
We all make mistakes. It happens. We all need second and third opinions rather often. We are in this world together often working toward the same goals. Not a one of us has even 1% of the answers. We each need help. In this case, you must understand the issue by now. We will not hold your hand forever. You have the answer and it is more thorough then we have taken the time to understand. Go ahead and spread the information. Cut the cord. Skip the bottleneck.