Hey.

To be eligible to NIT you need to have a minimum of 75% in your 12th boards exam or belong to the top 20 percentile of your class if you belong to the general category. And the cut off marks of JEE mains to be eligible for NIT in 2018 are 74 marks. Hence considering your jee marks you seem eligible.

With a score around 200 you can get admission in lower NITs. You can refer to the link below to knwo about cut offs of various NITs.

https://www.google.com/amp/s/engineering.careers360.com/articles/jee-main-cutoff%3famp