What does "God has a plan for you" mean?

My family is Catholic...I have never grown up going to church however I have always had a strong desire to go. It probably sounds weird...but I feel like I've had signs or messages in my life that have sortof directed me to go church or even God. Its hard to explain. Anyways I have recently started going to a Christian Church..which I really enjoy even though sometimes its hard to understand everything. What does it mean when people say God has a plan for everyone...does that mean I have a destiny?? That things and my fate are already determined? Its hard for me to fully understand/grasp that because I know we all are able to make choices and change our life...but is that too part of God's ultimate plan? Any thoughts would be appreciated