Hi @Littletink_. @Former-Member invited me to come and give another perspective on your situation. My take on this is from the side of someone with the mental illness. I have bipolar 1 and my companion is an unofficial part-time carer for me.
From my experience, the kind of depression you describe in your partner is a deep hole indeed. I have experienced a similar state of being a number of times. Perhaps the worst was about eight years ago when I had the final breakdown of many out of my employment. At that point I went to bed for about 20 hours a day for at least nine months (I'm not actually sure of the amount of time it went on because, not surprisingly, I don't remember much about that time). I actually feel I needed to do this long sleep to survive the absolute mental and emotional chaos going on inside me. No amount of pressure to do things would have helped me in this state. I was severely disabled by my condition and simply could not stay awake.
The recovery from such an extreme state of depression has been slow and is ongoing. As @Former-Member has said, bipolar is a very serious mental health condition. In my experience, I have never had anything resembling full remission from it. On the positive side, there is definitely the possibility of great improvement in our condition. From really not caring at that time whether I was alive or not, I now enjoy my life and savour many wonderful things about it, even if I struggle with simple things every day and am not as capable in these ways as most people.
My companion (we have been together 14 years) did look after me more than usual during the time of my deepest depression. However, he never took on the role of 'nanny' to me. He maintained his work, regular routine and hobbies during this time, making sure he was caring for himself first of all, so that he would be able to care for me as best he could. This meant that sometimes things were completely neglected by me and he didn't pick up the slack. I'm guessing he made ongoing judgements about what were completely crucial forms of help (like feeding me), and what could be let drop if need be without loss of life or limb. At the same time, he treated me respectfully and as an equal human being. I have huge gratitude towards my companion for the way he has cared for me so sensibly over many years.
The one thing in your latest post that rang bells to me was that you only see locum GPs who move on all the time. I would strongly suggest you find a GP who can treat your partner in an ongoing way. I have been seeing my doctor for eight years (since the big breakdown) and she has helped me enormously, in terms of mental health, physical health (very important in supporting mental health) and in ways that are more related to social welfare. This has only happened over time and the trust I have in her has only developed over time too. I also think it's crucial with bipolar to have a good ongoing relationship with a single psychiatrist too. These two medical professionals are the bedrock of all treatment in my experience. Related to this, it seems possible to me that your partner's medication regime is not working very well for her. It often takes quite some time to strike the best medication mix for the individual person. Again, this is more likely to be found with a stable doctor and psychiatrist.
I've written a very long reply here. I hope there is something useful in it for you. Kindest wishes to you and your partner.