Hey aspirant

First of all you can't change your category for jee advanced. Category of jee advanced and jee mains should be same. So you cannot appear jee advanced as ews category. chances of getting admission for top NIT colleges is low for above mark. You need to score 96 percentile above to get admission in NITs. For EWS candidates 66percentile is minimum for qualifying for Jee advanced. As you didn't enroll your ews certificate you belongs to general category and 77 percentile is required for qualifying for jee advanced. there are many other state level colleges providing admission on basis of jee mark.you can try in that colleges  For more details on college prediction refer below link https://engineering.careers360.com/jee-main-college-predictor?utm_source=qna&utm_medium=jee_cp