keep pushing, i think you are in the right place especially after you passed that exam, i dont know about italian but in our country you could say “here” or “yes” or other thing you dont stutter on, i had the same problem so i used “yes” in university. luckily for me my classes were big so rarely i had to answer questions, i am sorry dont have an advice for this, but if you have panic attacks or anxiety i think its worth it to visit your doctor maybe he can help you, there is medicine can reduce this