reflection or reflex?

I should have talked... I am so failing this class.
I should have noticed... I wonder if ever I am going to be very good at this.
I should have asked... next time, next time.
I should have stayed... it was too late.
I should have smiled... I think I'll try harder.
I should have walked around more... but I was feeling rushed.
I should be grading... but this won't take long.
I should not sleep tonight... but I might be unpleasant.
I should have known...