Hi! I know you are confused with this process as I was. I am set for my interview for my AOS; I have NEVER seen a Civil Surgeon and did not receive an RFE for that; USCIS have scheduled me for an interview... I ask my lawyer about this; and he said that for K1, as long as we have filed for AOS within a year of the medical exam that we have in our home country then we are not required to see a CS; or else I should have received an RFE instead of an interview date... Hope this helps.
Ralph
