Yash your 19337 rank with 45 marks in SC category is not at all sufficient enough for you to get admission even in lower NITs like NIT Hamirpur, NIT Agartala etc. until and unless you have state quota. 

You can still check out the following links for knowing the last 2-year cut-off of all the NITs and IIITs which will give you a fair understanding of your position:

• https://engineering.careers360.com/articles/jee-main-cutoff-for-top-iiits
• https://www.entrancecorner.com/engineering/jee-main-2017-cutoff/

While checking the NITs cut-off make sure you check the closing rank of your home state NIT under the home state quota and other states NIT's closing rank under the other state quota.

You can also find out the list of private engineering colleges where you have a high probability of getting admission by going through the following link:

• https://engineering.careers360.com/jee-main-college-predictor

Feel free to ask if you have any more queries. All the best!!