Ibis...hiding all the way over here. What am I going to do with you?
Venastat is an "anti swelling" herb with diuretic properties, called horse chestnut. I've seen what this one can do first hand (on a friend's hand, in fact). It is marketed as anti varicose vein, but its antiedemic (anti-swelling) abilities were known long before that.
Dandelion root is a natural, potassium sparing diuretic which is very mild. It may actually be too weak to help you.
I've only used/seen use of these on a temporary basis. I don't know how effective they (or any other diuretic) will be long term. Your body has that nasty trick of adjusting to things like changes in water balance.
I'm afraid that there is no herb which I could find which has been shown to increase thyroid receptor levels. Right now I'm on plan B, which is increasing the sensitivity of existing receptors.