If you are OCI Card holder and you have a Passport from the US, you have to take admission through DASA. According to the official guidelines available at: http://nchm.nic.in/sites/default/files/2018-11/DirectAdmissionSchemeforNRFNPIO.pdf, inspite of completing the relevant education qualification in India, OCI card holders have to take admission through DASA alone. This is the excerpt from the official guidelines:

Student who is a Person of Indian Origin, who held a passport in a country other than Afghanistan, Bangladesh, Bhutan, China, Nepal, Pakistan, Sri Lanka and provided with an Overseas Citizen of India Card (previously PIO Card) by Govt. of India. If a PIO passed the qualifying exam (i.e. 12th equivalent) from India, even then they will be considered for admission under this category.