Hey there

If you won't get any seat in spot round then your nit Silchar seat will not be affected if you have not frozen it. But as you have got nit Silchar in regular rounds then you might will get good college in spot round.

Check JEE main counseling

https://www.google.com/url?sa=t&source=web&rct=j&url=https://engineering.careers360.com/articles/jee-main-counselling-seat-allotment/amp&ved=2ahUKEwjUxti1wq_jAhVbaCsKHXKIAbcQFjAAegQIAhAB&usg=AOvVaw1zz-ym-Wk0sgWmgeJyDfFi&ampcf=1

Good luck