A lot of symptoms overlap between hypothyroidism and Chronic Fatigue and it's easy to be misdiagnosed - the main one being fatigue. Other common symptoms of hypothyroidism include weight gain/inability to lose, constipation, hair loss, puffiness in the face (especially, under the eyes), joint/muscle pain.
Do you know what tests your doctor has ordered to rule out/confirm hypothyroidism? I hope s/he's not simply relying on a TSH test because you'll need a lot more than that. In addition to TSH, you should be getting Free T4 and Free T3 (as opposed to Total T4 and Total T3), and antibody tests, Thyroid Peroxidase (TPOab) and Thyroglobulin Antibodies (TgAb). The antibody tests would confirm Hashimoto's, which can cause symptoms of hypothyroidism before TSH is elevated or FT levels are decreased enough for a diagnosis.
You should also be getting a thyroid ultrasound to determine whether or not you have thyroid nodules. An ultrasound can also help to diagnose Hashimoto's since Hashimoto's produces certain characteristics of the thyroid.
In addition, you should ask for Vitamin B-12, Vitamin D and Ferritin tests. Vitamin B-12 deficiency can cause the most intense fatigue you can imagine, along with some other symptoms. All 3 are needed to properly produce and utilize thyroid hormones.