Paul, in Philippians 3:10-12, gives us the other principle for discovering your purpose,
That I may know Him and the power of His resurrection, and the fellowship of His sufferings, being conformed to His death, if, by any means, I may attain to the resurrection from the dead. Not that I have already attained, or am already perfected; but I press on, that I may lay hold of that for which Christ Jesus has also laid hold of me.
Paul said, "I am pursuing my purpose," but it was a purpose based on knowing God. Look at what he said in verse 10, That I may know Him.
The understanding of his purpose came out of that primary desire and pursuit of knowing God Himself and living in intimacy with Him.
Perhaps the most important thing you could do in your life right now is to just lock yourself away, grab your Bible, and go sit at the beach. Find that place of communion with God. As you get to know Him, you will also discover your own heart and the dreams and desires that God put within you.
They are there. They may be covered with debris, they may be covered with dust, but they are there. You can find out what they are if you will develop that intimate relationship with God.
It is in closeness with God that His breath blows the dust off of undiscerned and unrecognized purposes and dreams.