Truth is, you may or may not ever "know" 100% that you are on track for God's divine purpose and it's ok! I have found that if we get busy doing the things He has already commanded us to do like love, give, and go then, amazingly His will suddenly becomes very clear. God is complex, but He is not complicated.
It's unfortunate when people get all twisted up about a lofty, glamorous dream position that they feel God is going to just drop out of the sky. Many wait for Him to say, "Hey, here it is! Here's the important thing your going to do that will gain you the respect and command of the world while paying you millions with a sign-on bonus." God doesn't work like that. He allows you to grow and He chooses to use you where you are FIRST. So, you don't have to shut-down your life and wait on God to do something miraculous. His word even gave us a little clue in Luke when He said, "Occupy til I come." In other words, stay busy til I get back.
I have a husband who is a physician. He didn't just wake up one day with a medical license in one hand and a stethoscope in the other. He worked very hard for years in undergrad and medical school and sacrificed greatly to make the dream a reality. He made daily decisions that were in line with his long-term goal. Now, he reaps the reward for that sacrifice and he will tell you that he feels that this was God's design. He absolutely had the choice to not be a doctor, but he put in the time that it took to become a very good one.
I don't want to throw a wet blanket on the fire of your dreams because you absolutely should dream! But, just like my husband studied every day for years to refine and deepen his understanding of medicine, you will have to hone your craft, work on your dream, or practice your ministry a little everyday.
Vincent Van Gogh said, "Great things are done by a series of small things brought together." So, taking small steps every day in the right direction is what will get you to where you want to be.
Proverbs 3:6 MSG says, "Trust God from the bottom of your heart; don't try to figure out everything on your own. Listen for God's voice in everything you do, everywhere you go; he's the one who will keep you on track. Don't assume that you know it all. Run to God! Run from evil!
Your body will glow with health,
your very bones will vibrate with life!
Honor God with everything you own;
give him the first and the best.
Your barns will burst,
your wine vats will brim over.
But don’t, dear friend, resent God’s discipline;
don’t sulk under his loving correction.
It’s the child he loves that God corrects;
a father’s delight is behind all this."
God honors faithfulness and honesty and humility. Trust Him. Do those things and He will direct your path. Take small steps.