What goes on in your head when you stutter?

What goes on in your head when you stutter? I'm always curious what goes on in people's heads when they talk. Especially if they can talk flawlessly without a stutter or any doubt in their mind that they are going to stutter (which I don't actually know but I feel). But I'm curious if what happens is similar to any of you community members and would like some help. I'm kind of a fast talker, especially at work bc it's fast paced and I work as both a server and a hostess. So usually I go through the same routine and use the same words. Eventually during my shifts I can't even say "thank you" or "have a good day" to customers. When I start talking I immediately think about what I'm talking about. I think about what words I'm going to choose and use and how to pronounce it. I start to worry about what words I'm going to use. Then I start worrying about one word. When I get to it, it's like there's something in my throat, on my tongue, in my mouth and I get stuck even before I say the word. "Uh. Uh. Uh." Or I'll start pronouncing it and get stuck on the first syllable. And when I get stuck I immediately worry about how my face looks, how my mouth is stuck wide open, how my voice sounds unsure, how people are looking at me. They immediately tilt their head and kind of come closer with this face that says "what is she doing?". I apologize after I can manage to say whatever it is I'm trying to say. I always feel so hurt and angry when they make that face-- or they immediately mock me right in front of my face. I feel like they're making fun of me, they're not taking me seriously. Anyways I'm curious. What about you guys?