American citizen living in South Korea

The issue date of my visa is 9/22/2011, my final entry date is 10/22/2012. The period of my sojourn is 13 months. I have been here since October it is now April. My alien registration card was issued on 10/20/2011. My vacation time is April 28th to May 6th. Do I have enough time left to be able to visit China? It has always been my dream to visit China. So please let me know.