How do I balance all this stuff?!?!

Hi new adult here, I’m about to be 20. I work full time as a manager, I’m a full time student, and I pay all of my bills. I still live at home though, because I don’t get paid enough to move out yet. I’m also a full time girlfriend. And I eat all the time because I’m stressed. How the HELL do I balance out my school, work, relationship, and exercise at the same time?!?! I’ve gained so much weight because I haven’t had time to take care of myself. Does anyone have advice on how I can help myself do better? Thanks!