OP, the good news is that you know what the problem is: you were physically abused by your brother, emotionally neglected and gaslit by your parents and grew up with a mother who was depressed.
That may come as a hard shock to read, and is a short form version, but you've been suffering for a long time and it's not fair to think that there's something wrong with you. There's not: some really bad things happened and your parents didn't protect you. You reacted to that (abnormal treatment) in a way that is completely normal.
Look up ACEs (adverse childhood experiences). They're best seen not as a diagnostic tool, but an indicator. Might be interesting to you.
As for CBT and the medications (do NOT stop the medications), imagine you have a wound on your leg. It hurts and won't go away. I give you some painkillers and show you how to sit so it doesn't put too much pressure on it. That's like medication and CBT in your case, they're not able to heal the wound. That's of course simplified, but gives you an idea.
EMDR and schema therapy have been mentioned and they're two good routes to try. EMDR is referred to as a relatively quick fix and it's important to understand that in the context of, for example, doing it after a car crash. In your situation, the issues are not stemming from one incident that happened 6 weeks ago, so it can be longer, per issue. I'm trying to get your hopes up, but not unrealistically and reading about EMDR generally focuses on single issue problems.
What is very important is that you are with someone properly qualified. I'd be looking for someone who is a counselling psychologist or clinical psychologist (both doctorate level qualifications) or a psychiatrist.
I don't know your financial situation and very sadly that can have an impact on things. If you can afford private those are the qualifications you should be seeking out. In the order I've listed them, but they're all good to start with. And note: counselling psychologist is not the same as counsellor, or someone who offers counselling, or a psychotherapist. It's much more highly trained.
It was mentioned that SSRIs can cause side effects and can actually be unhelpful. This is true. However, it's dangerous to just stop taking them, so please, if you want to do that, don't do it without proper medical supervision.
As you're looking at reading, then a good place to start would be Bessel van der Kolk The Body Keeps the Score. I would really recommend it.
I can recommend other books too but need to get up. Let me know.