Check your bank..
If you paid application fees via your personal account, you may want to check whether those have been cashed.. If cashed, you may ask for cancelled checks which will give you the SRC#.. I sent my package on 3/11, got RD & ND 3/12.. Got all the receipts around 3/22 except the all important 485 receipt which is lost.. But I got my SRC # number through cancelled check...
Good luck..