Hello, I'm so, so sorry. That sounds so hard, I can't image how painful and difficult it must have been and how much strength it must have took. I think that some psychologists or health professionals feel that the young know nothing of real life and real suffering or maturity, because they didn't encounter much themselves until they were older so couldn't possibly see you as an equally mature and affected human being by your earlier experiences. Very odd.
One of my friends who has PTSD went to the doctor for sleep medication and he told her 'you're a bright young girl, you don't need medication', when she really f*cking did. Some people are incapable of listening truly and seeing you and your problems as they are. But not everyone, we just have to keep going until we find the right people. I have found people who specialise in trauma treatment or who have experience in and an understanding of my traumas are the most helpful, so I'd recommend researching online. It is really painful and angering when people don't get it and they compound the problem but having someone who does get it, really brings such relief and help so it is really worth researching and finding the right person for you. Both my counsellors have been very helpful to me, because they validated that I had a problem, and could listen and understand when no one else could (either through training or through their own experiences).
I'm really sorry for everything you have been through and what you are going through now. Trauma does change us but we don't have to live with prolonged and intense suffering. I have felt completely changed, angry, depressed, panicked, scared I was losing my mind, horrible countless nightmares, panic attacks - but over time, with the right support, they have lessened and many have been eradicated. It is possible to find yourself again and some sense of wellbeing and balance, but that doesn't take away what happened to you.
I've also found strengthening my own resources to be a big help, through friends, yoga, healthy eating, exercise and I also do some compassion meditation when I get too overwhelmed by anger, as living without peace is no way to live for me.