You are making a mistake to say that a visa was available for you in February 2016, the Nvc contacted you in February 2016 because your priority date (March 2004) is nearing to be current., they contact early so they want you to have all your document in place by the time your priority date becomes current. The Nvc visa bulletin for September. 2016 say that they are now ready to issue visas to people in your catergory f4 with priority date upto october 8 ,2003 .
