I’m very glad you wrote. It is a step in the right direction that you are acknowledging that you tend to blame others when, chances are, most of the time your anger is unreasonable and irrational. It could be that you are suffering from depression and anxiety. Depression doesn’t always show up as sadness. Sometimes the primary presentation is irritability and anger.
In spite of being a “downer” and negative, you do have friends, so you have positive qualities and aren’t angry 100% of the time. No one would tolerate that for long. So let’s build on that positive information. Let’s start by assuming that there is either a biological factor or maybe that you don’t have sufficient coping skills for dealing with it when you feel overwhelmed.
It would be a good idea to make an appointment with a mental health counselor to get a full assessment and to consider options for treatment.
The good news is that you are only 20. With some treatment to help you get to the bottom of this, you could have decades of a much happier life where you are no angrier than most people.
I wish you well.