Well I believe your percentile is quite on a lower side and your CRL rank would be easily over 1.2 Lac, so with this getting DTU or NSIT is far from reach.

Now for NIT's, it really very slightest of chance you get a seat at NIT and that too would be a very low ranking NIT and an unpopular branch.

So I would adivce you to 

1. Prepare well for state exams like WBJEE, UPTU etc as these state colleges too provide some good state engineering colleges which are far better than the lower 15 NIT's.

2. The other best option is to prepare for BITSAT. By prepapring for good one month you can score over 300 on BITSAT easily. From this you can get BITS Goa easily which is far better than any of the NIT's (leaving the top 5 NIT's)