Possibility of change in Date of Birth (DOB) after 30 plus years

Mine real DOB is 1974 but due to clerical mistake it got changed to 1972. In UP board village school from class 6 to 8, we were 2 students of same name (X Kumar) and same father name (Y Kumar). After class 8, I chosen Science stream and other guy went to Art. School Clerk made a big mistake here and shuffled our SR numbers (Student Registration Number) due to same name and same father name, SR Number is like a Primary Key in school, and because of this my date of birth (1974) went to that guy and his date of birth (1972) came to me. I had given 10th board and dob (1972) got printed on my 10th marksheet. I got to know this only when leaving school after 12th and going to get admission in Graduation. Clerk accepted his mistake and helped me to prepare the legal papers to get this corrected but it did not happen due to financial problems. When I grow up with age, I started feeling depressed because of my DOB and when I think about it, it hurt me lot. Is there a way, I can get this corrected now? I have all papers like class 5th and class 12th leaving certificates from two Govt schools where my DOB mentioned as 1974 in both, legal papers that got prepared in 1991, school application with sign from Principal where school accepted the mistake. Any way possible now, how can I get this corrected?