I applied n 400 April, 05 2006. I was denied because I did not remember my wedding date. So I appel I got interview again 6 month ago they told me they need to review my paper. Still I'm waiting for answer.

I got my green card from my wife she is usa citizen I have 3 kids from her we still married my younger daughter is 8 months old.

At present, N-400 takes between 6 months to 2 years depends on many factors, background check could be the reason of delay. If your case delayed just because you failed the interview, you should establish more evidence of relationship, and most important document, tax return.