How long has it been since you sent in the EAD and AOS applications ?
The rules on EAD's are that if its been more than 90 days since you received an NOA for the EAD application, then you can arrange an infopass appointment at your local office to request an interim EAD. The problem you have is you don't physically have an NOA to use as the starting point for this 90 day count.
Did you receive any email updates from the USCIS website that alerted you to the fact that something was being mailed ? If so you could use this date (plus about a week or so) to give you a rough idea of when an NOA *Might* have arrived.
The problems I forsee with an infopass appointment is that without an NOA in hand, they may be unwilling to give you any concrete answers regarding the mythical 90 day count. Also, as you don't have an NOA you probably haven't attended a biometrics appointment. Your EAD won't be approved without this appointment because they need to run your name and fingerprints through the FBI systems before they will approve an EAD application. I guess you could use this fact to get past the thought that you missed on a job because whatever the USCIS sent you went missing. Without biometrics you won't have been approved.
My guess is that the document(s) that have gone missing are the NOA's saying that applications have been received, not notifications that applications have been approved.
Not sure if I've been any help there or not.
Best of luck with everything. You can take a look at my timeline to see how long I had to wait for my EAD !!)
Mark