I would reach out to local congressman/senator or House of Rep to find out why your case is pending. They can get information accurately from USCIS
If they inform you that name check is pending, request them to assist clearing this. They might not agree to help. Then write to Mrs Bush and ask for assistance,state that you have exhausted all avenues possible. Your case has been pending for more than 2 yrs in 485 stage, they will definitely help clearing that. My husband was in a similar state, writing to Mrs Bush helped get the name check cleared. Took 2-3 mths but it was worth it. Search the forum for formats for the letter, there are tons of cases that have sought out the First Lady's assistance and succeeded in clearing name check.Good luck!!