Normal dimensions for a thyroid lobe are usually "4 to 6 cm in length and 1.3 to 1.8 cm in thickness. The isthmus measures less than 4 to 5 mm."
I'm assuming .06 cm, .09 cm, .07 cm and .02 cm are all actually 0.6 cm, 0.9 cm, 0.7 cm, and 0.2 cm.
Your dimensions at 3.2 x 0.6 x 0.9 cm and 3.9 x 0.7 x 0.7 cm are on the small side for thyroid lobes for an adult, but that can be influenced by body size, etc. (and if this is a child, that is very different than adult thyroid sizes). 0.2 cm for isthmus sounds about normal.
Parenchyma refers to "the functional tissue of an organ as distinguished from the connective and supporting tissue". Heterogeneous describes how the texture appears on the ultrasound - if the texture of the thyroid tissue all looked the same, it would be described as homogenous or isoechoic, heterogeneous indicates there are brighter and darker areas (probably a speckled texture). Often heterogeneous texture on an ultrasound can mean there is a problem of some sort, such as autoimmune diseases like Hashimoto's or Graves, but I wouldn't immediately assume that without more information.