Hey Aspirant !
With 518 on your dashboard, you actually have a chance of procuring a seat in the state of West Bengal.
Although last year, a score of 518, bagged a seat in the Calcutta National Medical College, but this year owing to the easy level of paper, it's estimated that the cutoff would go up.
Accordingly, you might not get a seat in the city of Kolkata, but you are most likely to grab one in the district medical colleges, most likely
1. Murshidabad Medical College
2. Maldah Medical College
3. North Bengal Medical College.

Hope this helps.
All the Best !