H1-B Ammendment or Extension

[a999]

Hi, My current H1B amendment is still in pending and my h1b status expires on 04/17/2018. Now I got a new project and I am going to start work there from 03/28/2018.

So now for my situation

Should I directly file h1b extension with start date as 03/28/2018 using the new project PO and letter

                                             or

Should I file an amendment with extension and start date as 03/28/2018 using the NEW project PO and letter

Which option is correct.