You should never be reluctant to ask for a copy of your lab results. They are yours as well as the doctor. If you are in the U.S. the doctor is required by law to give you a copy upon your request. So I suggest that you get copies of your last couple of sets of thyroid related test results and post results and reference ranges here so we can better assess your status.
It is a good practice to always get copies of lab results and write on there how you were feeling at the time and what meds or supplements your were taking and their dosages. These records are very valuable for future reference to monitor your progress.
I also know that it is apparantly a multinodular goitre. The whole goitre is enlarged. When I went for a cancer test a few years ago the woman said they're so many which one am I supposed to test and then decided to test the biggest (it was fine).
Unfortunately I don't have copies of my blood tests. When I go for tests the response I usually get is they're perfectly normal. I then feel a bit silly asking for them (I'm not very good at pushing things like that, stupid I know). I do get told that they are well within normal limits though.
It was only when they tested for antibodies and it came back positive that I got forwarded to the hospital. I haven't been for several years but last time my report was all fine let's wait for something to happen.
Let's start with info on causes of goiters.
"A goiter can develop as a result of numerous different conditions. It can be associated with over-function of the thyroid gland (hyperthyroidism, or excessive thyroid hormones) or with under-function of the gland (hypothyroidism, or inadequate levels of thyroid hormones). Also, some goiters are associated with normal levels of thyroid hormones. Both inflammation and tumors can cause thyroid enlargement. Sometimes, the entire gland may be enlarged in a symmetrical pattern, while in other goiters, nodules, or enlargement may develop in one part of the gland only."
I'd really like to see your current blood test results and reference ranges shown on the lab report. For now, please post previous test results so we can see what tests were done and where they fall in their range.