Its a lot to put into a post but here's some good sites:
http://thyroid.about.com/cs/thyroiddrugs/a/armour.htm
http://www.mayoclinic.com/health/drug-information/DR602011
Since it's not just T4 like levothyroxine (synthroid and others) but a natural combination of T3 and T4 your body absorbs it differently. Some here swear by it - others can't take it.
I am on the generic due to insurance. The Dr says that means Levoxyl may vary ea Rx. What makes Armour diff? Other than it not being synthetic?
Have you tried a specific brand of levothyroxine? Some of us work best with a particular brand name. Personally, if I don't get Synthroid then it just won't work for me. Others have very different reactions. Talk to your Dr. about switching brands before you just throw in the towel and go for Armour (which is very different)