No Captain's Log or EDDiscovery running to give you a log of your travels, which should allow you to follow your trace of breadcrumbs back?
If you left after the 2.1 drop, your game logfiles will contain all the star systems you jumped to, set up an account for yourself on www.edsm.net , get some API keys, install Captain's Log and EDDiscovery, switch eddiscovery to upload and download from EDSM using your API keys, and then let both have a go at your netlogs. CL for yourself (nicer interface), eddiscovery for the community.
EDIT: Fixed the URL of the Elite Dangerous Star Map.