Hey,

I do not agree with AAAA. I had the exactly same situation as you have right now. You can do processing from here and is far more easier than proecessing from nepal.

Follow those steps-

-Wait till your number is available. You can check in website to know when your number is available.

-go to nearist USCIS office  in office hour and consult in public window in office hour, get the form needed , and they may give you list of place where you can do doctor certificate.

-take a appointment for application, you can take a appointment form www.uscis.gov and go through INFOPASS.

-follow up them as they tell.

Trust me it is very easy. Even i do not recommend to hire any attorny for this. Good luck