I can't stop thinking about my girlfriend being pregnant, and I don't wanna be a father.
What concerns you most about being a father?
I like my freedom too much and I want to be able to fuck around
If you are about to be a father, it is time for you to start being more responsible.  You should support your girlfriend and be ready to step up  and be the best father that you can be. It is important to realize that at this time it is no longer all about you.
I don't know what I'm going to do about my girlfriend's pregnancy.
It's common for expected parents to feel confused and overwhelmed. Have you considered how your girlfriend is feeling about all of this? Maybe try to talk to her and you can support one another better.