As children I think we are more connected with the spiritual world than we are as adults.
As a child you knew without a doubt that you were destined for greatness. As you lived life and accumulated experiences, you let the world seep into your mind. Making you question and even doubt your purpose. Convincing you that what you absolutely knew as a child, was a lie.
I think your prayers were answered, and you just didn't accept the answers. You were told to hold on, have faith, stay positive, reconnect with the spirit inside of you and pray some more. It was sent to you in various ways by lots of different people. Since you were looking for something more specific, and you were looking for something to happen now, you didn't accept those answers.
Now negativity is seeping into your mind, festering in your soul and fulfilling its purpose. Which is to keep you from becoming great.
This is just an obstacle that you have to overcome, in order to achieve that destiny, that you know is yours. Your questioning, your lack of hope, and disbelief are all obstacles, that you need to move out of your path first.
Yes, you are destined for something important, but you are not fully prepared for it yet. Instead of searching for the meaning of your existence; make your existence have meaning. Use this time for personal growth, to concentrate on helping others, to learn, to travel, to experience life in its fullest.
And greatness has been set aside for you, but this is your time to show that you actually deserve it. Why should it just be handed to you? Why should it just be handed to someone who questions the validity of that destiny, who doesn't believe in that destiny, who is ready to quit when the road seems blocked, and who believes that this life is mediocre?
Many important people found their paths later in life, and overcame many obstacles to show that they were worthy of their destinies.