On my Understanding of Sarcasm

For almost my entire life, I have struggled to understand sarcasm.  I have interpreted the literal meaning (or denotation) of people's phrases instead of their figurative meaning (or connotation) for a long time.  For example, when I first read Swift's "A Modest Proposal" (sometime before my junior year), I actually thought Swift really wanted to use children as "food" (405).  Since then, I assumed Swift was twisted and insane.  It wasn't until my tenth grade English teacher clarified that Swift's paper was a satire that I started viewing him as not so crazy.  Unfortunately, my new understanding of "A Modest Proposal" still didn't prepare me to identify sarcasm all the time.  When having conversations with people, it often takes me five to ten minutes to process any sarcastic remarks.  I have to constantly distinguish between the literal meaning of words and the connotation of words.  Oftentimes, when I am listening to a speech or reading a sarcastic essay, I need more information than what the speech or essay provides to help me understand any sarcastic remarks without taking them too literally.  (I apologize for being too repetitive.)  For instance, if a teacher jokingly says that he will take a point off of my test for asking a stupid question, I will need to know for sure that he will not take off that point in order to understand his joke.  If I am missing this piece of information, a heated argument will likely initiate between the teacher and me.  Fortunately, I now am getting a grasp of what sarcasm is like (thanks to 11 AP English's stressful workload), but I still have a long way to go.