Ok here's the update: since i didnt have any serial, mac address or find my mac, During the changing of all my passwords i was in DropBox website and found out that they kept track of the last connection in each device I had installed DropBox. After a few hours I noticed that a new IP address was shown in that list, it was the guy using my laptop who didn't know how to format it and that I had dripbox installed. I searche online
With that IP ADDRESS (he used it at least 3 times) and foun out hich carrier he was using for internet connection. Through a contact inside the carrier I found all the infos about this guy. Sent the police over there and they found my laptop!!
If police in my country was more efficient, they would have found that info fast, but I had to do it myself; and they still haven't cought him since he had a stolen laptop and declared he didnt know anything. Plus he posted on facebook a photo of my comp the same day or the day after the robbery...!
Anyways, hope dropbox can help more users like this!