You are not the only one! Many fellow Americans (living and working outside of the US) are not aware of their obligation. That is one of the reasons why the IRS has implemented several programs such as the Voluntary Disclosure Program for Overseas Americans, which is designed for those who were not aware of their obligations to file taxes in the US and therefore non-willfully failed to report and file their tax obligation. It is important to get help in deciding for which program to file, and to ensure that you file correctly.
We strongly advise that you start the process of getting tax compliant. Americans Overseas is here to help you get as much information as possible on the topic, and to help you find the best possible assistance from tax specialists who are well-informed and specialized in this complex system. The IRS runs a program for those abroad who were not aware of their tax obligation in the US.