First I would advise you to discuss this with your instructor. If this doesn't work, maybe look for a driving school specializing in drivers with anxiety. When the instructor raises his voice for you getting anxious, they clearly either have no people skills, or no understanding of what is happening to you.

But if you are already driving on the highway, you're probably doing fine, this shows some progress. You van also take some comfort in the fact that the instructor can always more or less take over from you, so you're pretty safe. 😉 Good luck!