You probably got the ole "not diagnostic" category, that means they did not get any cancer cells, but that does not mean there is not cancer. I had the same, had 4 follicular lesions, turned out benign follicular clusters, but I had the surgery on the right side, and after pathology report came in I still had incedental papillary cancer in the thyroid tissue less than 2 mm, which unless they stuck the needle directly into the cancer, they would have a benign result. If you are not having symptoms, wait awhile and repeat.
They probably have problem to differentiate between follicular lesion [surely benign] and follicular neoplasm {50/50}. You may have to ask the lab to send the slides to experienced cytopathologist so he can look at them.
Other solution is to repeat the biopsy; the follicular neoplasm {50/50} has "SCANT colloid with Micro- or Macrofollicular structure [mean the cells formed a tissue in the nodule].
The benign follicular lesion has "watery colloid" in large amounts with some loose follicular cells.