I'm sorry your question didn't get an answer before. Perhaps people felt a little out of their depth and were not sure about how best to answer. I'm afraid I just missed it as I haven't been around much lately but Marie has brought it to our attention. Luckily I can share my experiences. I just hope it's not too late to be of use to you.
As Marie says, there is evidence to suggest that T3 (and to some extent levothyroxine) enhances the effects of tricyclic antidepressants but I also think that thyroid hormones can help with the depression itself. I read something yesterday that suggested that there was a strong correlation between bipolar patients and subclinical hypothyroidism. This leads me to believe that getting enough thyroid hormone is essential for good mental health.
In my own experience, I have suffered with severe mental health problems requiring hospitalisation. This all started in the years before I was diagnosed hypothyroid but I was experiencing symptoms of hypothyroidism long before I was diagnosed.
My psychiatrist at the time decided to try T3 in combination with my other treatments and, after a few months, I was totally "cured". I was able to lead a pretty normal life until they decided I didn't need the T3 any more because I was "cured". This saw me back in the mental health unit
A couple of years after this, I was finally diagnosed with hypothyroidism and the doctor I saw was sensible enough to see that I had responded very well to T3, so that was what he prescribed. I was well for a few years, able to work full time and enjoy life, until it was decided by another doctor that I had to have levo like everyone else. Since then I have been struggling with depression until I found Thyroid UK. I followed the advice on here, started taking NDT and now I feel so much better. There is more tweaking to do but I no longer have to take ANY psychiatric meds at all! I am also working full-time, helping out on this forum when I can, teaching karate once a week and having fun with my kids. Previously I could barely get my kids to school without it feeling like climbing Everest.
This is my personal experience and the same won't be true for everyone.
As your ft3/rt3 ratio is so low, I really do feel that your T3 could be part of the problem. In this case you would probably be better with T3 than levothyroxine, at least for a while.
You may also want to check your cortisol levels. Please have a look on the internet regarding adrenal fatigue. You may find that you have low cortisol (symptom of adrenal fatigue) which could explain your low ft3 ratio and some of your symptoms. Be aware that regular NHS doctors don't believe in the existence of adrenal fatigue, but you should be fine with a good thyroid endo. In cases of adrenal fatigue, you would be better taking T3 than levo.
Regarding your ferritin level; it is very low and won't be helping! I also struggle with ferrous sulphate for the same reasons as you. I take spatone instead. You will need to start with more than one sachet a day in the beginning because your ferritin is so low but after the first few weeks you should be ok with one a day. Take it with fruit juice (not grape or grapefruit) and make sure you are also getting enough vitamin B2 (riboflavin) as that will help your body store the iron. You may find taking vitamin C before meals helps with your iron levels too, and it should also help with any adrenal fatigue.
I'm sorry if this is all a bit muddled. I'm not quite with-it this morning I hope I have been able to help at least a little bit.