I can confidently say something may be wrong, using myself as an example. i had the interview in may 03, last week in november i called the 800 number to find out what was wrong, i got a mail from Fresno, CA later saying my application is being reviewed by a supervisor, when i physically went there, the customer service person called my interviewing officer to find out what is going on, i later met with her and was able to find out what the problem was, although she did not detail it but she said once an application is flagged for any reason, they will be looking at everybit of details which may now totally delay the process. being me i was able to nail it down, now i have supplied the needed docs through my lawyer and hopefully my case will be resolved,
Do not wait anymore, visit them, talk to your congressman, someone must tell you what is wrong with your application.