I echo what HVAC said.
Being that you are 50, it is not unusual that you missed some periods. That is very typical in the perimenopause time frame. Also, many women complain of digestive symptoms including bloating likely due to the hormonal changes (although gluten can cause that too in some people). And Hashimoto's may or may not be a contributing factor to both the bloating and menstrual cycle changes.
Let us know what you find out from the doctor. I was over-treated for a benign ovarian cyst (my uterus, ovaries, and tubes were removed) and discovered that this is much more common than I ever could have imagined. Hopefully, whatever is causing your symptoms is nothing serious.
I know you are scared. A woman unless she has a family history of ovarian cancer or the BRCA mutation only has a 1.4% of ovarian cancer. Benign cysts can cause the same problems. Try not to worry until the doctors are sure. It is common to not be able to see an ovary. Gluten can cause bloating if your body does not tolerate it.
Alex