Any tips on getting over my mild stuttering?

Any tips on getting over my mild stuttering? A couple of years ago, my stuttering was kind of bad. However as I grew older, my stuttering naturally went away. Currently, I am a 21 year old guy. Now, I can carry out pretty much any conversation with almost 0 stuttering. I have no problem saying the vast majority of the words out there, whether it's during a simple conversation or while giving a speech to a crowd. The only problem is that there's still a small handful of words I simply can't stop stuttering over. Almost unanimously these words start with "st-". For example, I always have trouble saying words like "student" or "study". However words like "star", "start", or "stable" I can usually get by without stuttering, but not always. The funny thing is, when I'm by myself I have absolutely no problem saying these words out loud. But as soon as another human being is nearby, I can't say it anymore. It could be because I start feeling anxious if I need to say these words out loud, but I don't consciously feel any anxiety. The words simply don't come out of my mouth easily. Any recommendations? It's a bi frustrating because I'm so close to being stutter-free