Hi Lisa... The only way malignancy can be determined is via Fine Needle Aspiration (FNA). If your doctor hasn't suggested this yet, you should ask about it.
"While thyroid nodules >5 mm were found in almost all patients with thyroid cancer (96.9%), they were also found in over half (56.4%) of patients without thyroid cancer. The authors identified three characteristics of nodules found on ultrasound that were significant predictors of thyroid cancer—microcalcifications (odds ratio [OR] 8.1), size >2 cm (OR, 3.6), and an entirely solid composition (OR, 4.0)."
Less than 5% of all thyroid nodules turn out to be malignant... however, no amount of statistics will tell you if "your" nodule is malignant or not. You'll have to undergo an FNA to know that for sure.
Has your doctor not followed up with you after this much time? If not, you need to contact them and find out what's going on...