Pain in my heart like Something is missing

It would feel like movie dialog, “But seriously now a days I am having a wierd pain in my heart like something is missing, something is not right…Like I am missing something. Many people will say Get a girlfriend or something like this. But I already have a girlfriend still I am feeling like Something is missing. This heartache is eating me inside. I feel like I am lost. To know about it more I went deep down in my heart, and realized that may be its because Life is not going the way I want to. I dont want to live a life of mediocrity, I want to feel each moment. But its not happening. I am 23 year old now and I havent done anything that I can say I have made any difference. I want to do many things like I want to be a writer, I want to be a movie director , Internet hacker.. I want to roam all over the world. I want to live a life with no limits but Fear of unknown is holding me back. I dont know what will happen. May be I want too much or may be I am thinking too much. But I know I have to work for it.