Just because your thyroid hormone levels are within the normal ranges, doesn't mean you don't have hyperthyroidism. We all need different levels and what might be good for one person may be too high/too low for another person.
You need to have thyroid antibodies tested to confirm whether you have Graves, but you also need to have antibodies to test for Hashimoto's. Although Graves Disease is the most common cause of hyperthyroidism, early stages of Hashimoto's can also present periods of hyper, alternating with normal or even hypo before settling into permanent hypo. The antibody confirm/rule out Graves Disease is Thyroid Stimulating Immunonglobulins (TSI). The tests you need to confirm/rule out Hashimoto's are Thyroid Peroxidase Antibodies (TPOab) and Thyroglobulin Antibodies (TGab). Both of these can also be present with Graves Disease, but if you don't have TSI antibodies, you don't have Graves.
A thyroid ultrasound would also be good as it will determine whether or not you have nodules on your thyroid. Typically, nodules are harmless and nothing to worry about, but sometimes, they can produce hormones independently of the thyroid.
Another condition to consider is diabetes. Some people have weight loss and other symptoms with onset. Ask to get a fasting glucose level tested, as well as an A1c test.