A question about I94 during OPT

[Solow2012 0]

Thanks your help in advance

My OPT is valid from 07/05/2013 - 07/04/2014

My previous F1 visa expired in 08/02/2013. So I made a international travel between 07/26/2013 to 07/31/2013, and returned US back before my old F1 Visa expired in 08/02/2013.

The special thing is that, officer give me a stamp, written

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F1 OPT Auth until 07/04/2013

July 31, 2013

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I re-entered US in July 31, 2013.

My previous stamp is

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F1 D/S

Aug 29, 2011

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There is no fixed date in the stamp.

Did the stamp in July 31, 2013 means that I could only stay in US until 07/04/2014?

My electric I94 record shows

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Admit Until Date: D/S

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My company filed H1b for me in 04/01/2014, and I am preparing documents for OPT extension.

Either by opt extension or H1B cap-gap, I think I could be valid F1 status before 10/01/2014.

What special thing need to do in order to continue working after the date in I94 stamp, 07/04/2014?

Thanks a lot