My spouse says that I am an angry person. She is correct, but I cannot recall anyone in particular who treated me unfairly. So, what’s up with my anger?
You might have what is called repressed memories in that you are in denial about some injustices from your past. Sometimes, we so respect our parents, for example, that it is hard to admit unjust treatment from them. See if this might fit your own case. At the same time, it can be the case that you are angry because you reason that the world owes you a lot more than is reasonable. In this case, you might have some narcissistic tendencies (a me-first mind set). This can be hard to admit because narcissism exalts the self. It takes the moral virtue of humility to see the narcissism and to willingly change the pattern.
For additional information, see The Four Phases of Forgiveness.