I'm in college and I don't have a girlfriend so I was wondering if it is my PMO addiction or something else
That is a false correlation: just because you don't have a gf doesn't necessarily mean you have a problem. The truth is that the world is trending towards superficiality, so many women and men are looking for one-hit sex. And let's make something clear: Having a girlfriend IS NOT what makes someone a good person. That being said, if you want a gf, you have to put yourself out there. Also, taking steps to solve your issues with PMO is always a good thing, not just from an intimacy perspective, but also from a psychological and physiological perspective. If you can eliminate your interaction with porn and sexual media and manage your masturbation habits, then you will grow more confident. Even so, it's still possible that you may not find "that girl" anytime soon. But if you are more confident, then you will feel better about yourself and you will have great opportunity to interact with girls.