I Did, But Why?

Came home, and was very tired. I'd been hungry (I think) for about an hour. Okay.
I made dinner--a quick stir-fry of spinach, snow peas, onions, garlic, and some chicken. Maybe 5 ounces of chicken.
I was only about a a quarter of the way through the meal and suddenly thought, I think I'm full.
What happened next was strange to observe as it happened, and made me feel some sadness.
I began to ask myself loads of questions: But am I?Am I just tired and think I'm not hungry? What if I get hungry later tonight? That didn't seem like a lot of food--I couldn't be full, could I? Then panic: If I don't eat it all now, I have to use the microwave to heat it up, and I'm not using the microwave!
And then that feeling of willed vagueness settled in, the slipping on of that mental and emotional blindfold: I didn't make a decision, I just continued eating.
Once I was done (and I ate it all), I realized I'd overeaten, and that my fears--first in the form of self-distrust, then of deprivation, and then of inconvenience--eventually led to the vague-ing out, and to the overeating.
I'm really trying to have compassion for myself throughout this process. Still, to see this reactive, fear-driven eating challenges that desire.