for the limit to exist, the left and right hand limits must be equal, so just make sure as the graph approaches -2 from the left it is not equal to the value of the graph when it approaches from the right. make sure when we are approaching from the right, we are defined at x = -2.
you graph does the job, but it is weird. if you extended it, and only left the dots at the ends, it would be better. how about this graph? the dotted line is not a part of the graph, i merely put it there to show you that the points were in line