Well, brother with over 1.5Lac rank you hold no chances to have a seat at NIT Trichy.

Rather I'm afraid that you cannot expect a seat at any NIT. 

But relax your preparations and toil is not over yet. With decent hardwork you can still pull up a great college.

So I would recommend you to 

1. Prepare well for state exams like WBJEE, UPTU and GGSIPU. Trust me, some state colleges (which these exams offer) are far better than bottom 15 NITs.

2.  Prepare well for BITSAT for a month. With rigrous study for a month you can expect to have a score 300+. From this you can easily expect a seat from BITS GOA which is better than any of NIT.(leaving top 5)