Help

Help I don’t know what to do anymore. When I’m by myself I don’t stutter at all. Not once. I’m fluent with every word and pronunciation but when with others I stutter and it’s hard to get out die words and I use fillers such as um and ahh but they get dragged out. I have a presentation in a months time and I don’t want to do it. I don’t want to stutter. I don’t understand why I do it in front of ppl I was speaking to my sister and I was stuttering and then she was like just get to the point. I feel embarrassed. It’s not fair.