Managing autistic burnout with demanding lifestyle

I'm a premed student working towards being accepted into an MD/PhD program but since getting into college I've struggled immensely with autistic burnout. I wasn't diagnosed until a few months before I started college and then honestly we never actually acknowledged or learned about what that meant. I was diagnosed and then just went on living like I always had and oh yeah +autism.

I've started therapy recently with a therapist specialized in autism but that's still taking time especially because there are several big areas to focus on.

I'm really trying to change my mindset past maybe "internalized ableism." I've tried to start accepting more that I can't expect myself to do everything like everyone else because it's not fair to myself.

But I'm really struggling with burnout. I have tried a lot of people's advice about it but it feels like I'm constantly in a cycle of extreme burnout. I feel physically exhausted. I want to work but can't get myself to do ANYTHING. Not just school.

I can't get myself to read what I want. To watch YouTube. I really only do what I absolutely have to do then sleep if I can. But I struggle to sleep a lot too.

I work about 18 hours on the weekends in retail, 9 hours at a lab on Mon, then I'm on campus Tues, Thurs, Fri and therapy on Weds. So I have an extremely full schedule.

This is what's expected of students who want to be part of MD/PhD programs. Idk how to sustain this lifestyle. I can't stop feeling so tired. I've been working hard to make positive changes in my life after growing up struggling with my mental health but I feel like nothing is working in regards to burnout.

The videos I've watched online are a little disheartening to me because I think the people who are giving advice just live a very different life with very different goals and I don't really have the luxury of what they're saying I "need" to be doing.

Does anyone here have any advice for having a very demanding lifestyle and goals but not burning out every week? Being a physician scientist is my dream but I'm just struggling and I'm hoping others may have some tips.