So I kinda had a similar experience, when I was in high school I had a cool math teacher, I walked up to him because I had a question to ask him but I stuttered on a word for a long time and he said something like “I’m sorry I’m too busy helping others” I knew he meant well but I was still upset. Luckily I had a counselor I would meet during lunch and vent to her about my school problems. She basically reassured me that he didn’t mean to bring you down intentionally. My advice would be speak to your counselor about your situation or speak to the teacher himself and tell him you want to read out loud even if you stutter.