Question about the model – Emotions v Feelings – What does our nervous system have to do with it?

I have a question about the difference between emotions and feelings. I believe that circumstances are neutral and I agree our thoughts lead to our feelings etc. I keep going back to the idea though, that there seems to be for me an additional line in the model after circumstance that would be “E” or Emotion. It seems that because of my context and history (my past experience and interpretations of them) certain circumstances trigger my nervous system that elicits particular emotions special to me and my “system” that seem to precede thoughts and coincide with deep-seated beliefs I have based on my life experience and interpretation of that experience.
For instance when my boyfriend doesn’t call for a few hours and he said that he would, I have an emotional response first (the neural pathway in my brain fires – pre thought – which creates an initial panic (or whatever the emotion is)) then I have the thought and the various feelings around that particular thought after the initial emotion – which could still be panic but most often its anger or fear or some other feeling other than the initial emotional reaction that feels pre-thought.
I know variations of this question are asked a lot but again it seems like for me there is a pre-thought moment of emotionality or nervous system response – say when I’m on a roller coaster – I’m not really thinking “I’m excited” or “I’m terrified” – it comes as a response to the circumstance and then later I might have the thought “This is fun or that was fun” which leads to the feeling of enjoyment.
I guess to put it succinctly: How does our nervous system play into the model?!