How do I manage my time with 5 classes, a part time job, and studying for the MCAT?

Throwaway account to maintain anonymity, but I am a junior at a T20 US university, taking 5 classes (all of which are mandatory for my degree), working 15 hours a week as a lab assistant, and studying for the MCAT. I really only have time to eat and sleep I'm kinda running on fumes, and I know I will burn out soon. I know this is short term (2 mo) but I really need to power through at this point. I usually work 8am to 3pm in lab on Mon, Wed, and Friday, and 8-12 on Tues and Thurs. Any advice on managing time with such a heavy course load, job, and studying for a crucial test really is greatly appreciated. Thanks!