Enlarged thyroid goiter please help!?

my thyroid has been enlarged for years now. recently when i went for my physical the doctor asked about it. i said it had been like that for awhile so she recommended a ultrasound which is scheduled for next month. the doctors always noticed it but just did a tsh test which was always normal.
i'm super worried now. i've been looking up info online and i'm scared i have cancer. i don't feel any lumps on it. what are the chances it is cancerous. it is freaking me out because i've had it so long. i don't have any symptoms of hypo or hyperthyroidism that i can tell. what else could it be? could it be enlarged for no reason? i just don't understand why doctors waited so long for me to do anything about it. they always made it seem it wasn't a big deal if the thyroid hormone tests came back normal. please any info would be helpful. thankyou.

The long standing (more then 5 years) diffuse swelling without or with few small impalpable nodules means that in most cases it is NOT cancer. The cancer is usually shows up as large single nodule, which is 鈥渃old鈥?on RAI scan test. To verify that you do not have big solitary nodule or lump on your neck do the thyroid neck check.

Here's How:
Hold the mirror so that you can see the area of your neck just below the Adam's apple and right above the collarbone. This is the general location of your thyroid gland.
Tip your head back, while keeping this view of your neck and thyroid area in your mirror.
Take a drink of water and swallow.
As you swallow, look at your neck. If the swelling appears uniform and no lumps are showing most likely there are no suspicious nodules.
Repeat this process several times.

Non painful enlargement of the thyroid is usually goiter and multiple tests of thyroid function such as TSH, T3, freeT4 should be obtained along with a thyroid ultrasound. If the thyroid is painful then a thyroiditis would be suspected. These disorders can be treated if you are seen by an endocrinologist. Another possibility is that this is not thyroidal enlargement but enlargement of the thymus or a thyroglossal duct cyst. Chances that you are dealing with carcinoma while possible is less likely. See an endocrinologist for evaluation

thyroid gland is enlarged if there is dificiency of iodine in diet.
thyroid gland is also enlarged in disease of thyroid gland where is over production of thyroid hormone. there are associated symptoms as well. on testing blood for T3,T4 and TSH only we can conclude and then treatment is to be taken accordinglyl.