H1 B expiring on 31st May 2013..

Please help!

My petition was applied and approved in the financial year 2011-12,and was valid till may-13.But i went for stamping last month only and the stamping is valid till 31st may 2013. Can i still travel before 31st may considering the validity i might get on I-94.

Or, what is the best i can do. Please also guide me for extension under CAP exempt in my case and the extension fee.

Thanks in advance.