There is a connection between the thyroid and adrenals.

If you suspect adrenal fatigue, you should have testing done at the doctors, to see what your hormone levels are.

"Adrenal fatigue" is a term that pops up commonly on the net, and may or may not be actually present. It is very subjective as far as patients go.

Many people cannot tolerate 5-HTP. If you makes you feel irritable or jittery, you should stop it.

Kavinace has phenibut in it-- and here is an article about it:
http://en.wikipedia.org/wiki/Phenibut

I think these supplements may have significant side effects for some people. Notice that phenibut has a suspected action on dopamine?
Well that would affect the heart as well. Dopamine acts on the heart.
This is what dopamine does:
http://heartdisease.about.com/lw/Hea...rt-Disease.htm
Drugs that increase dopamine in the body like Wellbutrin, and stimulants may affect heart rate.
So getting a medical opinion for your suspected adrenal issue would be a very good idea right now.

This is a conversion chart for NatureThroid:
http://www.nature-throid.com/conversionChart.asp

Typically people are started on a very low dose, in the beginning, to get used to it. Starting too high may lead to heart palpitations, etc, and other symptoms.

At this point, for you, I'd consider doing one thing at a time. Get the thyroid working properly at the right dose, and the adrenals may follow and improve. I really do think your supplements are problematic.