I always feel insecure, think negatively, always mad, and think deeply. is it affected my brain?

Psych eval will help: Don't worry about your brain at this point. But do try to find a good psychologist to do a full evaluation. The results might point to a physical brain issue - but that's way less likely than stressful life circumstances. Before, or with, medication, I'd urge CBT therapy that could teach skills for managing thoughts/feelings/behaviors. Best wishes!