Are you sure the bit is .1181"? Are you using climb or conventional milling?
Try drilling a hole with the .1181" dia end mill and measure the diameter. The hole size may give you and idea what to expect when milling with that tool?
With the holes being larger than drawn and the islands being smaller it seems that maybe the bit is larger than you thought or maybe there is some run-out at the end of the bit(bent tool?) Try figuring the average of the hole sizes and islands to see what size tool would produce those dimensions and then try using that size to drill a hole, if it works then use that size for the tool dia.