Your marriage can be registered under the provisions of special marriage act only because you are not an Indian citizen now and holding a foreign passport.
Even though you are a Hindu by religion and hold OCI card, since you are a foreigner, you are required to register your marriage under the provisions of special marriage act only.
The NRI status can also be given to citizens who live abroad but have the roots connected to India whether through their parents or guardians. On the other hand, OCI cardholders are foreigners or citizens who want to work or to study within the Indian territory.
In India, civil weddings are governed by the provisions of The Special Marriage Act (1954).
You’ll need to submit your own documents to prove your identity.
In addition, evidence of eligibility to be married is usually required. Anyone who hasn’t been married should obtain a single status affidavit (in the US), a Certificate of No Impediment (in the UK), or Certificate of No Record (in Australia). If you’re divorced, you’ll need to produce the Decree Absolute, or if you’re widowed, a copy of the death certificate
In case a marriage between an Indian and a foreign national is to take place in India, generally its required to file a notice of intended marriage with a Marriage Registrar of your choice in India. That notice is required to be published for the stipulated 30 days. At the end of the 30 days the Marriage Registrar is free to perform the marriage.
The notice of intended marriage can only be given in India, if at least one partner is permanently and the other partner temporarily resident in India.
a citizen of another foreign country may be required to present to the marriage officer a “no objection letter” from the Embassy or Consulate of his country, as well as proof of termination of any previous marriages.