You have to wait. Your SSN should come in the mail within a week.
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Sent: 2/12/13 to Dallas Lockbox
Delivered: 2/13/13 Routed to Nebraska
G-1145: 2/19/13
I-797C Received: 2/22/13
Biometric Letter Received: 3/4/13
Biometric Appointment: 3/26/13
Approved: 5/13/13