Not everyone gets approved right away. Some cases gets transfered. When a case is transfered, the applicant is called for an interview at the local office. The interview is generally very simple and straight forward. At the end of the interview, they give you the approval.
Now, keep contacting your congressman, he is your best bet. Or if you have a lawyer that would be good too. Generally the USCIS will not entertain your requests effeciently.
As far as whom to believe, of course I do not know. But I would tend to go with the congressman. Ask him/her to send a status enquiry and to officially find out where the case is (Nebraska or Baltimore). They should be able to do that easily. This is why they have case workers.
As for the worry. You should not worry too much. There is nothing you can do. As long as you have your asylum approved and you have the documents to prove that, it is a matter of time, that is all. However long it takes is a matter of convenient. I know it is easier said than done, but that is reality. As long as you have your an EAD and can work, it is only a matter of inconvienience to renew that every day.
Now, having said that, I encourage you not to worry and keep contacting your congressman but be "cool" and polit in order not to frustrate them.
Good luck and keep us posted