REGARDING: wondering if I can take Actalin while on Levothyroxin which I have been taking for years. During that time I've lost most of my eyebrows and gained quite a lot of weight.

The ANSWER to that is IRRELEVANT: if someone has been taking Levothyroxine FOR YEARS they clearly haven't received any help from COMPETENT Physicians, and the Thyroid has atrophied to where it won't produce anything - it just "passes on" the Levothyroxine.
If BIG PHARMA companies weren't PROSTITUTING the FDA and lying to doctors in their "information" to just promote THEIR PRODUCTS, that patient MIGHT have had their Thyroid saved by PROPER treatment ...but clearly it's FAR TOO LATE now.