A related discussion, 1.1 cm rounded nodule in jaw area was started.
Heterogeneity is typical of thyroiditis and Hashimotos (chronic lymphocytic thyroiditis) is the most common type. About 10-15% of patients with Hashimoto's have 'normal' antibodies. So, with a slightly high TSH and a heterogeneous gland on US, this most likely is Hashi.
The other possibility is a recovery from a subacute (painful) or silent (painless) thyroiditis. In these situations, rechecking TSH in 5-6 weeks should determine if the thyroid medication is needed -- ie, in transient thyroiditis, the TSH should normalize (0.3-3.0) and in Hashi, it may typically remain elevated.