Need help figuring out references

Hi everyone! I'm hoping to apply for jet this fall, however I'm struggling with figuring out who I can use for my references. I am a recent university graduate however I never really connected with any of my professors or at least with professors that would be willing to write a reference letter. So far I have my boss at work as a reference but I'm wondering if I can also use a co-worker as well or if I need to branch out somewhere else. I'd appreciate the help, thanks!