Ok firstly, if you can write well this is a fantastic experience to reflect on in your application as to your tenacity and courage despite what I would consider near overwhelming odds. Plenty of people in all kinds of adverse situations have gone on to become great doctors: teen mums, people with chronic health conditions, refugees, you literally name it... I highly doubt you'll be the first person an admissions team has seen that has your background. I have a similar background as you, I wish I could say I am a medical student now, but I'm not, though I am applying this September! I went through a brief depressive phase for a while thinking I was past my expiry date , until I realised I absolutely am not and I can be a doctor.
It won't take you 4 years to get there... I would advise if you have no qualifications at all to start with maths + English GCSEs (whatever the uni specifies as necessary) and study for those during one cycle. Then immediately after once you get results in August start an access to medicine course. During this time get some work experience, probably as a HCA, or given your background maybe look into becoming a mental health support worker, as I think you could firstly and foremost do truly meaningful work for people who were struggling like you were, and secondly given your background, saying you've done this can help emphasise your 'I have grown stronger from this experience and now want to help others' / 'this experience will make me a compassionate and understanding doctor' vibe, as you need to reassure medical schools that your past history isn't going to impact you now as an adult medical student; this should be emphasised as well in your reference. Your reference can be a tutor btw, maybe hire one now and see them every week or month even while you start the process, so when the time comes to apply in hopefully 2 years, you will have someone who can give an exemplory reference for your character and why you're not just academicably able, but truly meant for this.
Regarding the GAMSAT, one university I wrote to said they would ignore my definitely not medicine standard grades if I took this exam and did well at interview. Maybe in your situation they might offer you a similar deal? DM for details as I don't want to give away too much publicly.
I think it would be tragic if what you went through as a child stops you from persuing your dream career. I'm in the same boat and the idea I'm barred from this due to my childhood fills me with equal heartbreak and rage that it can still control me like this. This simply isn't fair and I hope admissions will see it that way as well, they seem to from my brief experience want to encourage more non-traditional and mature students who have our backgrounds.
I wish you the best and if you want to DM then that's cool, just send me one