Dear Aspirant,there are good chances that you may get into IIT,NIT,GFTI based on your ST category rank. But I cannot guarantee that you will surely get a seat in the above mentioned colleges. Branches such as Computer Science Engineering and Information Technology usually have high cutoffs so you have more chances to get mechanical,civil, electrical engineering seats. You must register for JoSAA counselling without any delay and do check out for alternate colleges. Hope for the best and prepare for the worst. Here is a link to a college prediction website based on your JEE Mains rank:

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