Greetings to you,

As per your rank in JEE Mains 2019 and unless you don't belong to Assam, I am sorry to say that you will not be able to get a seat in any branch of NIT, Silchar. The home state quota could have made the difference but with othe state qouta, it is quite impossible. Good luck. 

Hello there. Since the choice filling time is over so you can't make any changes to the choices you have filled. And yes you should wait for other round as since their are 7 rounds, you might be able to grab the seat in a y of the round.

Hello there !!!! Based on your rank it seems improbable that would get a seat but still you should wait for subsequent rounds. The cutoffs keep changing each year and you never know , you may get the seat in subsequent rounds. So just wait for further rounds. If nothing good comes out of it then you can try out other college options or maybe private colleges too. Hope this helps.