Have valid VISA, I-94, I-797B, but I797A Expired. Can I stay in US and apply for extension?

I had valid VISA, I-94, I-797B till Sep 2017.
I have filed for Amendment in Feb 2016 as my client location changed and it got approved and I got I-797A, but only till January 2017. (I-94 attached till January 2017)
In August 2016, I visited India and while returning to US in the port of entry I got I-94 till September 2017, as per my VISA expiry date.

So can I stay in US till September 2017, and file my extension now? Please help. Thanks!