I am writing down this to discuss your experiences with congressman as well as discuss when it is appropriate to contact congressman.
Generally contact your congressman for help ONLY IF all of the following is TRUE.
a) if your priority date is current
b) it has been over 5 months since filing of your 485 and 485 is still undecided
c) your 140 is approved
Only then you will benefit from congressman's intervention. If any of the above is false - then there is really nothing that you can do other than wait because USCIS and DoS can/will/could and should take the necessary time to process your case within the rules they operate in.
So do not contact your congressman prematurely. But do not hesitate if all of the conditions above are true for your case.
Good luck.