Do you have any documentary evidence as to your actual date of birth like hospital records 

2) after lapse of so many years registrar of birth would not change date of birth in your birth certificate 

3) 

You should apply for correction of date of birth certificate and other records by filing a petition before the Judicial first class magistrate (having jurisdiction over school).

4)  an affidavit along with all records(school leaving certificate etc) is required to be provided by two persons who have personal knowledge of your date of birth(parents, aunt's , grand parents etc).

Once government record is updated in DOB registered it could not be changed.

You can in case of affidavit of parents ,school leaving certificate obtain court orders for change of date of birth 

You can correct the name by following the procedures for name change.

But you cannot correct the date of birth so easily.

You may have to obtain court order directing the registrar of births and deaths to incorporate the correction after you convince the court with satisfactory documentary evidences to permit you to correct the date of birth.

If your DOB given in the school certificate differs to that of passport then the school certificate would be sufficient.

May take  a year or so 

contact a local lawyer in Gujarat 

Under Section 15 of Birth and Death Registration Act, the Registrar of Birth and Death (Municipal Authority) has power to make correction in birth certificate. Following is the procedure under Births and Death Registration Act for cancellation birth certificate …

1. Submit an application to the Executive Magistrate/Tahsildar/Mamlatdar for direction to municipal authority for correction of birth certificate.
2. A notarized affidavit of applicant stating reason for correction of bc.
3. Surrender the incorrect birth certificate issued by municipal 
4. Notarized affidavit of mother and father supporting affidavit of applicant stating the birth took place at home.
5. Executive Magistrate/Tahsildar/Mamlatdar will give direction to municipal authority for correction birth certificate.
6. Take that direction to municipal authority and apply for correction of birth certificate.
7. Municipal Authority will issue a correct birth certificate.
8. It will take about two months to get such certificate .

First try to take approval from birth and death department of your Village or city office. And than if you have valid reason that date and name was incorrectly inserted by your parents initially that has to get approval by court as well.

It's time consuming as first you have to apply for concern department and later on in the court or simultaneously have to apply.

It is a process through court of law. 

The time taken for disposal cannot be predicted. 

Besides,  you may get the relief of change of date of birth only if the court is satisfied or convinced about your pleadings in this regard. 

Looks like you will have to file a court case to get your DOB corrected since there is a very long long in getting this correction done.

File a declaratory suit; and get your correct date of birth declared from court. Thereupon, get your correct DOB inserted in all your documents. 

It's better you change your DOB in your passport and other documents rather than change of DOB in your birth certificate as that would require proof that you were born on the day you want to change it to.

To change the date/place of birth in the passport, you have to apply for a “Re–issue” of passport and get the specified change done in the personal particulars. According to the new guidelines, Passport authorities can consider requests from any applicant requesting a change in date of birth, regardless of when the passport was issued. Your birth certificate would suffice to change your DOB in passport along with some other documents for which DOB can be changed very easily online.

Affidavit from parents and school leaving certificate would have no bearing as they would not be accepted to change dob.

Changing of DOB in birth certificate would not be possible in absence in any documentary evidence. You should do do as advised above.

Obtain 'Birth Certificate Update/correction Form' the municipal corporation office or gram panchayat where your child took birth. Obtain an affidavit from local notary and approach the officer regarding change of name in the birth certificate. Make an affidavit on a non-judicial stamp paper of minimal and mention the reason of name change. Fill the correction form and submit it to the municipal corporation along with affidavit or certified copy with judge original signature. After the completion of the application process, publish the advertisement in the local newspaper and your state official Gazette publication.

- As per law, name or DOB in the living certificate or educational certificates cannot be corrected after two years from the date of issuing the same. 

- However, you can correct the same in all the documentary proofs after submitting the proofs of correct name & DOB 

- Since, your all the documents are alike , then after submitting the proofs of your passport and living certificate before the Birth registrar you can request to issue a birth certificate or if issued then move an application for correction. 

- If earlier your DOB certificate not issued by the Registrar , then you can get it after submitting the documentary proofs of residence in that place of your parents including you. 

you can go for rectification of the records in municipal Corporation

1. Your father shall have to execute an affidavit before the local 1st Class Judicial Magistrate affirming that his son's name and date of birth has been wrongly registered in his birth certificate as Xyz Patel & 15-Sept-1988 in place of Abc Patel &15-May-1988 which is required to be corrected now by amending the birth certificate accordingly based on the instant affidavit.

2. After the said affidavit is affirmed, you can apply before the appropriate authority to issue you a fresh birth certificate making the said corrections.