Hi Jenn24291,
I am so sorry to hear that you are feeling so horrible. I was recently diagnosed with Hashi's, but I have been feeling like garbage for a long time now. Like you, I have been very confused and incredibly frustrated and angry. What gets me the most is the inability of many endocrinologists to diagnose people with thyroid disease accurately and treat them until they say they feel better.
There is a great web forum for thyroid disease with people who know much more about what might be happening with you than I do. You'll read many stories similar to yours.
http://www.realthyroidhelp.com
I am being looked at for Cushing's disease as I write this, but that is a very rare disease. I only mention this because you wrote that you had a huge weight gain in one year and that is something that happens to you when you have Cushing's.
I know it is a lot to think about when you don't feel well. Hang in there and keep looking for answers! You are worth it!