Good Evening

Hope you are fine

As per your query, yes!!! you will be eligible to appear in NDA 2023. As per eligibility criteria for Age is that you must be in the age of 16.5 and 19.5 years to be eligible to appear for the NDA, and as you said that your Date of Birth is 6th February 2004, so in 2023 your age will be approximately 18-19.

Other Eligibility Criteria:

-> Nationality: Indian
-> Education Qualification: Must have passed class 12th with Mathematics and Physics as compulsory subjects from any recognised board or council.

To know more about NDA eligibility criteria checkout given link below:
https://competition.careers360.com/articles/nda-eligibility-criteria

Hope you found it helpful
All the best!!!