Well- I used to get heart palps all the time. They would last for minutes, and were worse if I was cold. It was very disconcerting. For an unrelated reason I went to the dentist for a teeth cleaning. It had been many years since I had my teeth cleaned, although I felt my hygeine regimen at home was good. After having my teeth cleaned, my heart palps completely resolved. Why, I have no idea. But they did. I have seen articles that gum disease and heart disease have a relationship. I have no idea whether this will be helpful to you, for all I know you see the dentist every 6 months, but it's what helped me.
I also have Hashimotos- are you taking replacement thyroid hormone? Nearly all my Hashi symptoms resolved after I went on thyroid hormone. I take the desiccated porcine thyroid, not Levothyroxine.
Your bowel issues sound like "rapid emptying" and is often related to food allergies.
Be aware that autoimmune conditions beget other autoimmune conditions. It's not unusual for someone with one autoimmune condition (in our case, Hashis) to develop others like Rheumatoid Arthritis, Celiac, etc. So you may have more than one thing going on. Some things that can help: identify if you have ANY food allergies, and get those foods OUT of your diet. In people with Autoimmune conditions, allergies cause the body to produce antibodies that then attack our own bodies. In my case, it was dairy. Have your serum D levels checked- most people with autoimmune diseases are very low on Vitamin D. I take 5000IU daily under the instruction and supervision of my doctor. Selenium helps protect the thyroid from autoimmune attack- make sure you are getting some in your diet.