You’re most likely not “stuttering” alone. You’re just alone with your thoughts, possibly after a long day. You may have had a drink or two. You just have a habit of criticizing your speech- every word, syllable, utterance, emotive gesture. Try recording yourself reading or speaking some time- your blocks aren’t as bad as you perceive them to be. When you block, you may feel like your face is exploding. If you watch it on camera, you’re just making a little eye movements. Try it some time.