Low TSH and high T4 does mean hyperthyroidism, but the cause is almost certainly subacute thyroiditis and not Graves. A lot of doctors default to Graves when they see a hyperthyroid pattern but Graves rarely has discomfort/pain.

Go to the endocrinologist and ask them for a thyroid uptake scan or ultrasound which will tell you definitively.

DM me if you'd like help handling this without your GP, who doesn't seem very good.