回複：J1 extension and J1 waiver:

This is the worst situation of J1.
Have your extension started? If yes, you don't have any choice, go back to China to fulfill two-year home country residency obligation.
If not, tell your sponsor that you don't want this extension any more. Since J1 has 30 days grace period, ask your sponsor apply H1 ASAP by premier process. If you are luck, you may get H1 approved within J1 grace period.