Your percentile is 65 and you belongs to the S T category. In my point of view your percentile is very low. You are talking about getting into the NITs but according to my opinion you can't even qualify the JEE Mains exam. This is the harsh reality. You should now try for another Colleges.See the last year's Cutoffs for JEE Mains

Category                           Cutoffs

1.General                         90 percentile

2. OBC.                             85 percentile

3.ST/SC                           More than 75 percentile

Here is the link of College predictor by Career 360 so you can check your college according to your Rank or Percentile.