Based on the information provided its very complicated and I have to break it down for you and will try to make as simple as possible so that you can understand it with ease, yes I do know that you have done lot of research and may have tried a lot of treatment but still I will try to explain hoping it will help in one or the other way.
(A) Lets start with HASHIMOTO HYPOTHYRODISM - Hypo - thyroidism - means low thyroid hormone, Not lets understand what thyroid hormone is for and what it does in simple terms.
Thyroid hormone is chemical substance produce in the thyroid gland located in neck, the main function is to help in METABOLISM - metabolism is a process by which body cell try to make a most out to available resources like sugar, protein , fat . The need for metabolism is to make other complex substances essential from simple ones or make simple substances from complex ones, (for. e.g. - we are making bread in the factory and we need flour as well as yeast and have to bake it at specific temperature to make a soft bread, this is way how simple substances are mixed and complex product is made , now on the other side lets take example of water purification , the water polluted water has various compound dissolved in and the purification is need to get simple pure substance ,This need some help from complex factories and chemicals,) now in our body we have CELLS which are factories and the HORMONE-required chemicals to produce certain substance.
Now in case of low thyroid hormone we have cell but due to lack of hormone we are not able to produce the required substance / convert to required form , so the over weight will result as body is not able to use the stored fat as energy source and will demand more food to be converted to energy.
(B) now HYPOPITUITARISM
- PITUITARY GLAND is located in BRAIN- now as we know that brain is a commanding center so the chemical secreted from the pituitary gland
is know as STIMULATING hormone - it acts as the stimulation of target gland to produced required hormone,
e.g- Thyroid stimulating hormone
is release from pituitary and reaches to thyroid gland via blood saying its time to release/make thyroid hormone and thyroid gland as per the command from brain will act producing and releasing the hormone in to blood so that other cell can get an help from the required chemical - like in case of bread we need YEAST.
So from this understanding the hypo pituitarism means brain lacks a commanding capacity.
(C) The issue that are present like 1) rapid heart beat, 2)sweating, 3)anxiety, 4)insomnia, 5) leg tremors occurs mostly due to the excess amount of thyroid hormone which is taken by you as some kind of tablet to replace the missing hormone , so a side effect from thyroid hormone replacement therapy
(D) Other remaining symptoms are from the menopause as in menopause their is decrease in estrogen and progesterone
level from the parent gland that is "OVARY" causing hot flashes/ cold flashes, breast pain, and other issues like migraine , edema can be seen ,
ALL in all its a combination of all kinds of hormone imbalance
, and the delicate balance is only done by human brain but in your case the commanding center PITUITARY gland is having issues, so we need to have the bare essential hormone replaced , by one or other means and for that hormone replacement is needed , more over the issues with sides effects will all ways be their as taking the hormone from external source can't be done perfectly (only god built can work in perfection).
Their is no way out if you don't take replacement hormones in required manner , major trouble and if you take them side effects will be waiting on other side, so a delicate balance can be done by continuous trial and error method by patient and doctor's side.
HOPE IT HELPS ,