Advice is rarely helpful. CBT and DBT are more focused on changing the behaviors, as opposed to addressing the underlying issues.
I recommend you see a psychodynamic or psychoanalytically oriented clinician who will not give you advice or direction. They will help you better understand your own thoughts and feelings so that you can better manage them.
This is not a quick fix. It will take time, and it won’t be easy. It may get worse before it gets better. It may mean questioning everything that you understand about yourself and the world, and finding yourself not knowing who you are. This is often a necessary step in figuring out who you are.
It’s important to understand that we develop our sense of self and the world around us based on our earliest experiences, and this happens without us being able to pick and choose what makes sense. We largely develop into ourselves based on our early caregivers and the environment we grow up in. This self-identity and world view often doesn’t match who we are as adults, and adaptations we made as small children in order to survive, can be self-destructive to our adult-selves.
Even the idea that nothing is helpful is very likely something you’ve been carrying with you for most of your life, and that is a great place to start. I wish you all the best in this journey.