How bad is your stuttering in these situations? Do you just get tripped up, or are you completely stuck at times? You need to determine whether these presentations are in your Desirable Difficulty range--too easy and you're not improving, too hard and you're overwhelmed and also not improving. If you're able to honestly assess this and objectively determine that these presentations are too hard for you right now, you can likely work with your teacher and agree on a easier but similar task.