Thank you to everyone for your helpful replies. I had a medical with Ofsted, which was pretty intense and very thorough, but I felt the medical assessor was really fair. My GP had to write several supporting letters to Ofsted as they wouldn't accept my psychologists letter (for some reason it had to be my GP who knows me less well, but my psychologist spoke to her first). The outcome was that Ofsted approved my registration, I was completely honest with them about everything - diagnosis, previous history of self-harm, the current therapy I'm having. I hope this gives some people who are worried about disclosing mental health difficulties for assessments like this some hope as I was so worried I would lose my job, but Ofsted did register me. Although the whole process took months.
My experience has been that Borderline personality disorder is one of the most stigmatized and misunderstood mental health conditions, for so many people who have this diagnosis it is as a result of complex trauma in childhood and early adulthood, but if you are a young woman, have a history of self-harm/ suicide attempts, it seems to be the popular diagnosis of the moment by psychiatrists. It feels unfair as this is a diagnosis that will stay on my records forever, yet has nothing to do with "personality" in the everyday sense of the word. All it really means is that I was severely traumatized and had difficulties dealing with that. I really wish they would change the diagnosis to Complex PTSD which would take away some of the stigma a diagnosis of personality disorder carries.
However I was honest about everything to Ofsted and they registered me, so there is some hope. To the mum who said she wouldn't employ me if she knew my history, I really appreciate your honesty, because probably many parents would feel the same way. However so many people go through things that traumatize them, or upset them in ways they later have a hard time dealing with. Rape and sexual abuse unfortunately happens to so many girls and women, and should we really be written off because of something which wasn't our fault, where we were the victim and hurt in devastating ways. The original trauma is so difficult on its own, the stigma and discrimination which comes with mental health diagnoses like BPD feels sometimes like being re-traumatized over and over again because it becomes something that is also shameful. But then in your shoes all I would want to do is protect my children, and the thing is because of what I went through, I am exceptionally protective over any child in my care, I make sure they are really looked after and kept safe.
Its so hard sometimes, because I feel like should I really have to go through the past every time I apply for a job and bring up these painful things that are so hard to talk about, to a complete stranger (medical assessor) and have them ask me deeply personal questions about my history? I feel like I can't leave the past behind, because I will always have to justify myself because of having a mental health diagnosis. I don't want to have to think about or talk about what he did to me, but it will keep coming up because of my medical records and I don't have the option anymore of closing the door on that part of my life. I will always have to justify that yes that happened, but now I'm ok. But sometimes I'm not ok, and yes talking about it may bring tears to my eyes or really hurt because it was a horrific thing he did to me. Yet I was the victim in it all, sometimes it feels like being a criminal, but having not committed a crime.
I hope it reassures parents too that Ofsted are very thorough in the checks they do for nannies (if a medical condition is declared). I had to provide several supporting letters from my gp and psychologist and they were asked to provide a very detailed case history of both past and current mental health. I then also had to attend an occupational health medical assessment which was also a very in-depth.