As I mentioned previously, there are reports that sometimes adequate treatment with thyroid meds and also some selenium (within daily recommended amounts) will help reduce the inflammation and swelling.
Since you have had an ultrasound, that is a good starting point. Now you need to periodically update, to determine if nodules are there and growing. So even if you should develop thyca, it is slow growing and you could monitor and take action to get an FNA to evaluate, for any further action needed. I don't know as much as I would like about this aspect of thyroid, so I recommend a good discussion with doctor.
I happened to notice this thread on the same subject. I think you can get some good info from it.
http://www.medhelp.org/posts/Thyroid-Disorders/Can-you-reduce-the-size-of-a-goiter/show/1187828
Also, please post your thyroid related test results and reference ranges shown on the lab report so that members can assess the adequacy of your testing and treatment. If you have been tested for Vitamin D, B12 and ferritin, please post those also, with ranges.