I developed PPD and borderline hypothyroidism after the birth of my child. My symptoms were similar to yours. Standard tests from my primary physician didn't catch the the thyroid problem. Fortunately, my physician was a sharp lady and she sent me to an endocrinologist anyway.
I've had excellent success with Fem Center in Colleyville. I see Dan Petrs. He believes in working with both the blood tests and the patient's physical symptoms. I showed up with a typed list of all my symptoms, which he appreciated (although most doctors might not care for) and we were able to get to the root of my issues fairly quickly.
I know some days it's hard to even get out of bed, much less out of the house to see the doctor. Your symptoms are real, and there is help for you. Good luck, and keep working at it.