I am now on 200mcg of Levo and still feeling rubbish, as I thought I would but I persevered but now its time to try something else. Under the direction of Dr S I will hopefully be trying T3 soon. However from the reading I have been doing and advice I have received I know before I start T3 that I need to make sure everything else is in sync (b12 etc) and have an idea of my thyroid status, so thats what I will do. Will have to be private though since, as Ive posted before, my GP isnt interested. So my question is - from what I have read it is best to wait until you have been on a Levo dose for 6 weeks before testing, is that correct? Could I go ahead and test b12, vit d, iron, ferritin etc now and then do TFTs in another few weeks? I know that sounds a silly question but I just want to get it right as it is a lot of money for them all. Splitting them would also spread out the cost!