Judging from your account, the most fundamental reason is lack of security and self-confidence. In addition, you are also a thoughtful and sensitive person, and you are very demanding and strict with yourself.
The first point shows that you have no self-confidence. Facing the unknown future, you are afraid, helpless and lonely.
The second point shows that you are a very sensitive and delicate person;
The third point is a reflection after you have experienced too many things, and all failures and setbacks are attributed to the inside.
You can feel that your heart has been struggling, contradictory and particularly depressed. You always put pressure on yourself unconditionally until you crush yourself. Insecurity is caused by your family education style, environment and childhood experience, while lack of self-confidence is caused by inner panic and high demands on yourself.
If you want to change now, such a problem can be solved, don't worry. But first, you have to solve your pent-up emotions. You have to release and vent them. Only by releasing the inner repression can we restore rationality; It takes some time and process to completely change. If conditions permit, receiving professional psychological counseling can help alleviate a lot of unnecessary pain and shorten the time. You can leave me a message if you have any questions.
I wish you get rid of your troubles as soon as possible and be happy!