Most thyroid nodules are benign (90-95%), and many people, especially women, have thyroid nodules and don't know about it. I was told that 20% of 20 year old women, 30% of 30 year olds, 40% of 40 year olds, etc. have thyroid nodules.
Because of your nodule size (at or greater than 2 cm) and because it is hypoechoic, it is important to get an FNA because those features put you at a slightly higher risk, but that doesn't mean your nodule is cancerous At this point we can't say whether it is something to be concerned about or not until you get the FNA, but as long as you get the FNA you are doing what you need to do to take care of the nodule.
I saw your other post that gimel answered - I'm surprised that your antibody tests were negative because numerous subcentimeter spongiform nodules sounds a lot like what I had (chronic untreated Hashimoto's which led to a multinodular goiter, so I had lots of nodules all over my thyroid). I know other things can cause multinodular goiter, but usually in countries where they use iodized salt, the main causes are usually Hashimoto's or Graves diseases, both autoimmune thyroid diseases, and the terminology used "numerous subcentimeter spongiform nodules" sounds very much like thyroiditis, compared to a normal thyroid tissue which they normally would describe as "Isoechoic" or "homogeneous". Hashimoto's can cause subclinical hypothyroidism where you have many, many hypo symptoms but your TSH is "in range" because your thyroid goes through fluctuations where it is attacked by the immune system, produces less hormone, and then TSH increases stimulating thyroid growth and production of more hormone. This can cause fluctuations of TSH and often tests show you have "normal" TSH when you are experiencing a lot of hypo symptoms. If you have results for your antibody tests, posting them here would be helpful because most of what you've described sounds like Hashimoto's to me (except for the negative antibody tests, but I don't actually know what was tested).
My thoughts are get your thyroid nodule biopsied because that is very important. If you have the results from your thyroid hormone and antibody tests, posting them would be helpful so we can actually see where your hormone levels are and where your antibody numbers are at (and if your doctor has actually done the correct tests needed to assess thyroid hormone and antibodies). If you are in the US your doctor is required to give you your actual test results if you request it (like a paper or digital copy).
I'm sorry you are going through this - this is pretty similar to what I went through a year ago, and I know how frustrating it can be to try to convince the doctors you have a problem when they say everything's fine.
Oh.. and to answer your other question here, you can have totally normal thyroid function and have a goiter or nodule. A lot of people have nodules and perfectly fine thyroid function, but your symptoms and the fact that you have lots of little nodules makes me think something else is going on in your case.
AS I mentioned and explained in my reply on your other thread, you should not automatically expect that an Endo will be a good thyroid doctor like you need. The probability is very low. I understand that you are focused right now on the biopsy, but that is only part of your thyroid issues. You seriously should not just wait for 6 months, while assuming that the Endo you mention is going to be the good thyroid doctor you need. That is why I mentioned that we might be able to help locate a good thyroid doctor if you are interested and will give us your location.