I've already had my thyroid checked twice and that isn't it. does taking my blood sugar neccesarily always determine diabetes?

No on the diabetes: A fasting blood sugar can easily miss up to 80% of diabetics. A better single blood test is a hemaglobin a1c. The test estimates your average blood sugar over the previous three months. At 5.6 and below you are good. 5.7 to 6.3 range indicates increasing risk to develop diabetes. At 6.4 you are now officially considered diabetic.