EB2 I-485 has been pending 3 years, 刚给USCIS打完电话

EB2, PD November 2003, I responded the I-485 RFE last year in August. The case has been pending since then. I called USCIS last November and was told that my case was under additional review. I just called USCIS a few minutes ago again, and the lady told me that she is going to schedule an appointment at local office in 30-45 days. What does this mean? Thank you very much.