M.,
I was hypothyroid myself. When I married my husband and went onto his insurance, my new PCP (his long time physician) ran his standard blood work on me. We were surprised to learn I was hypothyroid. A few years later, when I went to see his FNP, she noticed a bulge in my neck, and realized that it was my thyroid gland; it had goitered (a cyst was on it, filling with fluid, slowly over time).
The FNP referred me to an Endocrinologist, who adjusted the medication that my PCP had prescribed, on a regular basis. He encouraged me, eventually, to have surgery to remove the goiter which had so far through needle biopsy been negative for cancer. Yes, a scary thought!
I delayed, and delayed and then began to have pain (this all took place over a number of years), and went to an Ears, Nose & Throat doctor who found no other reason and was also suspicious of the goiter; he in the end convinced me to have the surgery, M..
They found cancer in this first half of my thyroid. The ENT also diagnosed me with Hashimoto's Disease (already mentioned by another response), officially (over time I had also been slightly overweight, dry skin, thin hair, etc). I elected to have surgery to remove the second half of my thyroid and they found more cancer. The cancer, my Endocrine doc tells me, is a later stage of hypothyroid~Hashimoto's Disease as the body continues to attack the thyroid as a foreign invader.
Long story short, just at age 40 I am a cancer survivor. You need to go see an Endocrine doctor and have ALL the possibilities checked out, especially since you sound so hypothyroid. You need to be there for your children, whether or not you end up going through what I did or not, the Endocrine doc is a specialist in adjusting the medication for hypothyroidism, and has more of the latest knowledge than even the best PCP MD.
Let me know what you do.
D.