how did plans get ruined for amir?

I think this is what you mean,

The next day, Amir left the hospital against Dr. Faruq's advice. He planned to use the money from the safety deposit box to pay his bills, leave Sohrab with the Caldwells, and fly home. When Farid arrived with Sohrab, he explained that there were no Caldwells in Peshawar, nor had there ever been. Farid drove Amir and Sohrab to Islamabad.