I am not sure what a blood test would add at this point, as it is primarily about getting you well. Generating a number in pmol/L that you are happy with is futile if you feel like crap.
What it does sound like you need is some menopause literate clinical oversight rather than chopping and changing your estrogen dose by yourself, rapidly reducing in steep drops.
I would be far more inclined to suspect the noradrenergic antidepressant that you are taking as the cause of tremors and palpitations etc rather than estradiol.
Do you have a supportive GP that you could work with to stabilise your treatment?
If not, I would save up for a further specialist consultation, even if that takes a while, and I wouldn't drop below 50mcg without a medical review because the long term health benefits such as bone protection, cardiometabolic health etc have not been reliably evidenced below this.