I just called the National Visa Center, expecting to be told again that they haven't even started to look at our documents, when the lady I talked to told me that our case was "completed" last week. This means that all of the documents need to be sent to the American consulate in Taiwan and we will have an interview with them, where they will decided whether we get the green card or not.
There's some confusion as to whether we schedule the interview with AIT after the documents get sent back to us, or the National Visa Center sends the documents after they themselves schedule the interview. The latter seems a little illogical because they don't know our or AIT's schedule. Wouldn't it be easier for AIT to schedule the interview of we ourselves are not allowed?
Oh well! The important thing is FINALLY after 1 year and 1 month our case is eligible for an interview. We just have to wait until then.