I'm so sorry to hear about your experience. I hear you. I relate so much to your words about not being adequately prepared for adulthood. This is a common experience for most people. Honestly, being an adult is super difficult, and you're definitely not alone in your experience.
I also want you to know that being behind academically or partaking in learning assistance programs is not a sign of weakness and incompetence at all. It just means that you have strengths and skills in different areas. I know plenty of very intelligent people who began their schooling life in various learning assistance programs, and they've become very successful in their chosen fields. It's also a great sign that you've recognised your need for help in this area.
Do you have any friends or family in your support network? These connections can help you cope with the stresses and challenges of everyday life. Depending on the kind of relationship you have with them, family may also be able to offer you some kind of financial, emotional, or work assistance if needed.
With regards to finding a job, my recommendation would be to find some kind of program that will help you build skills and experience to put on your resume. There are always government assistance courses and training programs (like TAFE) that can help you upskill and find a job that's right for you. It may help to conduct a bit of research into what's out there, and find something that suits you.
Is there a reason that you feel you've been struggling to stay in a job? Does it have something to do with self-doubt or perhaps lack of experience? What kinds of jobs have you had?
If you are feeling up to re-entering the workforce, there are lots of entry level jobs, like packing shelves at supermarkets that can offer you valuable experience, networking opportunities, and could even be a gateway to other jobs once you've built up your confidence and competence.
I would also recommend, if you are able, having a chat with a psychologist, GP, counsellor or therapist about your experiences. They may be able to offer you some more professional advice and help you set a direction for the future.
Thinking about the future can be scary, I understand. But you're still so young, with so much life ahead of you, so you've got plenty of time to experience things, get your foot in the door somewhere, and find a career path that really resonates with you.
Take care, and I wish you all the best in your situation.