Don't know if you'll ever visit this site and see this reply but here goes anyway.
Read, read, read, read, read, read.. and read. Research is your friend. If you don't fancy books then watch YouTube videos, but you must learn as much as you can about what is going on with you, what was going on in your childhood, what was going on with the people who influenced you. And over time your brain will expand and the idea that it was not your fault will begin to seep in. There was nothing that could have gone or should have gone differently.
See, if you never find out that people you had to deal with are actually sick and could not have acted any differently you will continue to internalize that there is something wrong with you to have deserved that treatment. Simply sitting in a room going over your life story while it can be helpful in your understanding to what happened can get a bit self flagellating - my childhood sucked, then my marriage sucked, now I'm alone, it sucks... It is good to do therapy but it is only ONE thing in the process. You also have to understand that it had nothing to do with you, and sitting in a room talking about your feelings and the events of your life is never going to get you to that particular understanding.
And DO. You must do things. The answer to boredom is DO. The answer to underachieving or underearning is not to be found in sitting on the sofa eating chips and lamenting underearning. And I say this from exactly that experience! I'm not on a high horse, at best a little pony trodding along learning myself. But what I do know is that sometimes your brain is not your friend. It will F you up. So as an example, I get myself all worked up typically about cleaning house. It overwhelms me. Why? Because I ignore it for weeks - I don't DO anything about it. Then I look at it and suddenly realize it's messy. And instead of my brain being a reasonable pal and saying "Oh well, Otter, you can't possibly do the whole thing before you pick up the kids" it says "OMG! It's so messy! I am a horrible person! A horrible parent! What kind of example am I setting! No one can ever ever ever come to my house it is too embarrassing. I am embarrassing! My children hate me..." you see what I'm getting at. And those voices don't even have to be loud! And I'm not even including the voice of my mother while I helpfully do for her since she lives hundreds of miles away and can't see my house. But I will do it for her, inside my own brain "(eye roll) Well Otter, you've NEVER been clean. You've ALWAYS been messy. You just CAN'T accomplish clean. If you'd only have done what I said...." See? Those voices are mean and debilitating and while they are chirping about it my head I can't focus, I can't breathe, I can't get started. So then the house gets even messier because I have managed now to avoid it even longer.
But if I hear those voices and say Shut up, and go get the cleanser and clean the bathroom counter, then they do dissipate. And voila one part of the house is clean. DO. That is all. Because listening to the voices inside our heads - even though we may not have put them there in the first place - is what we call wallowing in self pity, a very unproductive state. So the thing that you least want to do, that seems the most insurmountable, that is the thing to start to do. Remembering of course that you can do only one thing at a time. Don't get me started on the perfect and end result voices!