OP, first of all huge sympathy because I do understand where you’re coming from. So first of all, please have a big imaginary hug in solidarity.
Secondly, not all therapies are right for everyone, and it’s good that you’re willing to try other therapy modalities despite your disappointing experiences so far. I hope it’s ok to share a few of the things that have been working for me.
In my 20s I had to learn some principles of acceptance and commitment therapy (ACT) - didn’t actually know that was what I was doing at the time, but I sort of had to teach myself those things. If I hadn’t managed that, I wouldn’t have made 30. So if you haven’t been able to access ACT yet, please do look into that.
Also, you don’t mention if you’ve tried EMDR therapy so apologies if you have and it hasn’t been useful for you. But it’s been very helpful for me and some of my friends (and an ex-partner) for complex PTSD symptoms, including some really awful childhood stuff. If you haven’t tried it, please do consider giving it a go. I thought it sounded utterly bonkers when it was described to me, my my ex talked me into trying it and it was a game-changer despite my scepticism!) You can have private sessions if you have the budget and have an EMDR specialist within travelling distance. Or there’s an app called Ed Can Help, which is a rolling monthly subscription (less than a tenner a month) - that’s what I use these days upon the recommendation of a very good psychiatrist, as I’ve also recently had some long-buried stuff forced upon me again. It sounds like you might need something specifically designed for helping work through trauma feelings, to help you process those alongside doing the inner child work.
I’m also having some transactional psychotherapy at the moment - I have some unfortunate life stressors I can’t do much about, and do need a bit of extra help dealing with things at the moment. This particular therapy is helping me understand where my feelings and reactions are rooted and how I can adapt to deal with them better. It’s not entirely about the inner child, it’s about the inner child in the individual context of you as the parent and the independent adult, and helping it become more secure.
I’ve also given in and gone on a low-dose antidepressant, which is making more difference than I was expecting it to - it’s not making me less miserable about the rubbish stuff I can’t control, but it’s doing wonders for my feelings of self-efficacy and determination to deal with the rubbish stuff.
You are amazingly strong to have got as far as you have despite your background and the things that happened to you. You don’t necessarily need to maintain contact with blood family members if you don’t want to. Having a “family of choice” instead is what gets me through. I have honorary sisters, an honorary brother, and some wonderful older female figures in my life who are all the things my mum wasn’t.
And having purpose is vital for your wellbeing. If you don’t love your job, that’s fine, for most people work is just a means to an end. if that’s the case for you, and if you have any time to yourself, you could do something you’re passionate about in the side - whether that’s volunteering with young people, maybe painting or another form of art, gardening/horticulture, studying for a certificate (or more) in something you’re interested in, or whatever. People often dismiss non-work activities as “just hobbies” as though they’re not important, but they can give you inner purpose and be a key part of the puzzle of being emotionally and psychologically well.
I wish you all the best.