Dear candidate,

The cutoff for JEE Main for 2019 for general category was 89.75 percentile as compared to this year's cutoff of 90 percentile, so would probably have not qualified as you said that you got 84 percentile. Now coming to your second question you would probably have no luck to get into a good NIT or IIIT so i would suggest going for a good local college that accepts JEE Mains. You can use the link given below to check what all colleges you can apply for.

https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

Hope this answer helped you.