No motivation (teen, highschool and work)?

Hi, I am almost 18 and I am in high school and I am working a 20 hour a week job.

This year my grades are going down and I have no motivation and I just escaped from an every other day attendance cycle (sort of). When I wake up in the morning I have become so tired that I forget to get dressed/ready for school, or my backpack, or pens and pencils. This is happening quite often. On days I stay home it is because I didn’t do my homework that was due that day and I do not want to get another zero on it.

When I stay home my mom usually calls me from work and its either I make the house spotless or I lose my car keys (sounds reasonable to me). I avoid going back to sleep because then I will not wake up until 3 those days.

I have the job to pay for my car insurance, gas money, snack/food money and school supplies. My mom would pay for this stuff, but I do not actually see her too often since she isn’t home too often.

Before I go to work, sometimes I will start to have slight panic attacks (not so bad anymore) because I am dreading it so much. I work as a cashier for a wholesale club. It’s in my opinion one of the better jobs somebody my age can get. The other cashiers are pretty friendly and I get along with them okay. Cashing people out for 4 hours straight though gets extremely boring which is what causes the panic before work. I work about 30 minutes away, so normally I come home from school, get changed, stop through a drive through and go to work. After work, I may stop through another drive through, or more likely get some snacks from a supermarket or something. When I get home all I want to do is listen to music and go to sleep which leads me to procrastinate and stay up until 11 and then not to my homework either.

I do not want to quit my job, because without it I would not have money for snacks, hobby stuff or school supplies. I want to keep my 20 hour weeks too so I can actually have a comfortable amount of money every week.

What I do not want, is to keep going down the road I am going. I want to snap out of this and get some motivation to do stuff again.

How can I get motivation? (Please, no friends, spiritual or hallmark advice either)