What’s the point in complaining about something when you’re stuck in the situation and nobody is going to do anything to help anyways?

Yep, this is likely what you're working on in therapy - the sadness and disappointment and maybe even depression that come after complaining and people do not support you or meet your needs. You were placed in a really unfair (ETA: and probably overwhelming and stressful) situation- raising yourself and your brother without people helping you. I'm sending you an electronic hug, Internet stranger.

I don’t have the full answer for you.

I will say that healing is not a switch to be flicked, but a process (often painstakingly long). And one of the first steps in that process is being very realistic with ourselves about what problems we have, how they are affecting us, and where they come from. In this sense, talking about them is very relevant.

It must have been very difficult.

Complaining could be a start? Maybe a better start world be to just do something that's risky. I don't know. There is no reason to live in pain like that.