You're 20 so I assume you either have a job or go to college, right? When would you carve out the amount of time to practice and play enough to drop 12-15 strokes from your current game? Unless you are independently wealthy or currently on a college golf team, that is.
Questions to answer:
How much time do you currently devote to the game?
What does the pro at your course think of your chances? Have you ever talked with him, or showed him your talent level?
How well do you do in the tournaments you play in?
Do you currently play with top-level amateur players and/or pros so you know what is expected?
Can you be a pro golfer? Sure, all you have to do is say you're a pro.
But can you be a touring pro golfer who plays week-in and week-out for millions of dollars on TV? Get back to us in a year, and you'll probably have your answer.