Does it have a big neck spread or just a little tiny one centered around the spot right behind its jaws? They all spread but the Eastern is the only one in North America with an extremely impressive spread. Also its a tough call just on pictures unless you are going by snout. Southerns have a VERY upturned snout similar to the westerns whereas easterns are more flat-snouted but they can still be upturned a bit with a rather fine point.

Don't get me wrong I fully believe that you may have a southern lol, where they are (scattered localities) they are quite common if you know how to look and then also they are becoming slightly more common at reptile shows. If you do have a Southern I hope you consider breeding in the future to reduce the amount of WC southerns because of how poorly their species is doing in the wild .