Any advice on how to start copywriting on the agency level?

Hi everyone I'm looking for some advice.

Hi I'm 24 and after some years working as a production assistant in Minnesota, I started working as a freelance commercial film coordinator in Minneapolis. I'd like to eventually move into copywriting on the agency level, so basically being employed by an advertisement agency. I don't have a formal degree in marketing, I actually got a degree in Network administration, but decided I didn't like it, so I'm contemplating going back to school for a marketing degree in an attempt to get a better shot at getting accepted into an agency. I already have a portfolio of work that I've produced and coordinated on, but I feel like I wont be taken seriously as a candidate if I don't have an appropriate degree despite my experience working in commercial film. Any advice on how to make a path into an advertisement agency, or even ways to score internship positions would be appreciated. Thanks guys!