The fact that the initial biopsy was benign is very reassuring. Only about 2-5% of nodules felt to be benign by needle aspiration biopsy will eventually turn out to be cancers. Thyroid cancer is such a slow-growing cancer and usually responds so well to treatment that 2-5% is a very acceptable rate of initially missing thyroid cancers (the alternative would be to send everyone with thyroid nodules to surgery - a strategy that the experts feel is unnecessary).
Benign nodules can grow, so the fact that the nodule is slowly growing is not especially worrisome. Still, according to the American Thyroid Association guidelines, thyroid nodules that grow should be re-biopsied to be sure that a cancer hasn't been missed. There is disagreement as to how much growth warrants re-biopsy. The American Thyroid Association guidelines suggest that it is reasonable to re-biopsy a nodule if the diameter grows by 20% with a minimum increase in two or more dimensions of at least two mm (0.2 cm). However, this is not an absolute rule, and you should probably leave it up to your doctor to decide when re-biopsy is indicated.
You need to ask for antithyroid antibodies (TPO and anti-Tg) and how about yor free T3, free T4 and TSH? How it looks your ultrasound of your thyroid? is it heterogeneous? It's true what your doctor told you about more then one nodule, They don't touch the nodules until they are bigger then 1 cm, but you need to do blood tests.