Congratulations for your result. There are various factors which determine the cutoffs so this changes every year. Now the cutoffs also depend on your category which you haven't mentioned. So considering you as a general category student and going by last few years' data, Computer Science seats get filled within 1700 rank after round 3 counselling. And Information Technology seats are mostly filled within 3100 rank. With your rank, it will be quite difficult to get IEM, Kolkata. Being one of the best private Engineering colleges, The cutoffs of IEM are quite high. Based on your rank you can expect only Mechanical Engineering in IEM. However, you can check for other private engineering Colleges.
http://engineering.careers360.com/articles/wbjee-cutoff
You can use our WBJEE College Predictor tool to know where you have good chances
http://www.careers360.com/wbjee-college-predictor