Native english speaker here. I have a stutter. Funny enough, I had to take the IELTS. It was certainly stressful, and I didn’t get a perfect score as I expected. It’s hard, even for a native speaker. In fact, I’d expect a good majority of native english speakers would fail the IELTS. In my opinion, it’s a rigged system that’s profit driven and unfairly discriminates. Don’t beat yourself up over this. Make sure they know you have a stutter. You will get paired with an experienced proctor and given extra time. It does help a bit to have slightly reduced pressure. Remember, you’re a rockstar. You have tremendous fortitude, passion, and drive from what you have to overcome on a daily basis. I think you’re awesome.