Giacomo Jacques BeharImmigration AttorneySan Diego, CACA licensed ·
Assuming you have all the proper documentation of your adoption you should be eligible to file for N-600 Certificate of Citizenship rather than apply for N-400 Application for Naturalization.
The best way to find out if you qualify for the N-600 is to gather all the proper adoption documentation and apply for a US passport at the passport office.