The Department of State is a big organization with a lot of stuff going on. You can read about it here.
I will leave it for others to fill in more about the organization. I am creating this page simply to let you know that you can check your case status by calling the DOS:
Dial 202-663-1225 Then press 1 and then 0 for an operator. Have your case number ready.
The operator should be able to tell you where your case is at, whether your packet 3 has been sent out to you and whether you have an interview date scheduled.