These sonographic, clinical and available laboratory findings are suggestive of either subacute lymphocytic thyroiditis or Grave's disease.
Thyroiditis is more common in young age, while Grave's is more common in midage females. Also, in thyroiditis the thyroid is usually average sized and shows heterogenous parenchyma, while in Grave's it's typically markedly enlarged with rather homogenous parenchyma.
In this case, the common findings between thyroidits and Grave's are the thyrotoxicosis and the increased vascularity of the thyroid.
For the above mentioned reasons, subacute lymphocytic thyroiditis is favoured over Grave's in this case. However, further laboratory investigation, searching for anti-thyroid antibodies, would be recommended to reach a final diagnosis, since it's positive in Grave's and negative in subacute lymphocytic thyroiditis.