Birth Certificate and DOB

Due to my December end birth date, I was facing problems in school admissions. So my parents submitted an affidavit to the municipality and got a birth certificate with a date of 6 months ahead. My passport was the first document that was issued, before this birth certificate issuance, and thus has the original DOB. All of my other documents - Class X, XII mark sheets, DL, Aadhar, PAN, etc. are issued on the updated DOB after my schooling began, EXCEPT my passport, which was issued when I was 2 years old. I have been denied DOB update from the passport office on the grounds of existing birth certificate in their records. I wish to pursue Master's education abroad, and am in desperate need of help. My parents had no intention of committing a fraud, and I, who is having to face the consequences of their actions, was 2 years old when this incident (Birth certificate update) happened. Please help me out, it has been my dream since forever to pursue education abroad, but a mismatch of DOB in my passport and all the other documents, will not allow me to pursue it. What can I do to have a consistent DOB across all of my documents?