I am a moderate to mild stutter but more on the moderate side. I think this isn't so much of low confidence (which obv still needs to be worked on) but having negative anticipation and menfisiting that in your life. Stuttering is a horrible issue from many people but how you describe yours, I feel like this is something that can be worked on and can be overcome. A lot of us have that same issue of saying "present mam" but it's normally with our names. Like you said it makes you nervous and because like us suffer a lot from easy stuff like that. As you said with normal people you can speak well. First you will need to so some self or professional therapy. Be ok with making mistakes even if it's your speech. Know that you can overcome this. There are some things that you can say in your situation. For example. It's your turn for row call. Add words like "yes present" or "good morning present" "hello present". You can even emphasize the word present. You can use your hands while saying present (using hands helps me a lot and others I know). All these are just techniques to use to trick your brain a little. The bigger picture is creating these new positive memories to remove that negative anticipation so that saying things can be normal. Maybe even to the point where you believe you're a good speaker and no longer identify as a stutter