Have they checked your thyroid antibodies? I'd guess autoimmune thyroiditis (such as Hashimoto's) which can cause the thyroid to swell
Please check the dimensions, looks like report is missing the third one for each lobe.
The heterogenious structure with tiny nodules is typical for thyroiditis (in the past or in the persent)--thyroid inflammation
I'm not well versed in reading ultrasounds, but wanted to say hello and WELCOME to th COMMUNITY,
Cheryl