I am currently in the process of getting my greedcard approved in EB2 category. My priority date is Mar 2010 and I-140 was approved on April 2011. I am currently in the 7th year of my H1-B visa expiring on April 2012. My last extension was on I-140 approval basis and was for 1 year, but i am trying to get it through FOIA.My company has not filed for I-485 and is also not sharing any documentation about the I-140.

My question is should I decide to move to another employer, can I port my priority date using the AC-21 clause, or is I-485 necessary to port it? Is there any other way i can move to another employment while retaining my priority date?