I’m sorry to hear that you are struggling. You have had to deal with so much your whole life, and it is completely understandable that you are feeling overwhelmed and sad. Growing up in a dysfunctional and unsupportive environment would have a huge impact on the way you view yourself, and it makes sense that you don’t think you will be able to achieve your goals and become an occupational therapist. However I want to acknowledge that despite all your setbacks, you are studying. It might seem like its harder for you than anyone else, but it is a great achievement to be accepted into that course, and to still be studying despite your difficult living situation. You are also doing what you can to get help by seeing a psychologist and reaching out on this forum.
You mentioned that you have people in your life who care about you, but you have a tendency to push them away, but you also said that you don't really have anyone to talk to when things get tough. I was wondering who these people are who care about you, and how might you be able to feel comfortable to talk to them? It’s great that you have a psychologist to support you, but sometimes it is nice to have a chat with friends.
You also mentioned something else in one of your replies about it not being beneficial to compare yourself to others. I think this was a really insightful comment, and I completely agree with you. This is your story, and only you know what your experience is, and comparing yourself to anyone else cannot bring about anything positive.
Good luck with everything and please feel free to write back here anytime you like!