For NIT in cse you will have to score just 65-75 marks ,with may fall to 75-85 percentile.even there is chance at mark lower than that if you float while counseling and you may also appear for csab round of counseling ,there will also be opportunity for you.

JEE mains cutoff for pwd candidates in paper 1 is much more easier than any one other examination. Just by scoring 1 mark or even 0 mark you would be eligible for appearing in jee advance ,so better you look forward for that .

and there is also chance for you because about 950 seat are there for open-pwd candidate.

let me give you one more boost up if you score 75marks in mains may be you gonna be the topper in pwd category as per 2017-18 data and you will have even better chance to choose nit of your choice.

hope it helps!!

good luck.