I'd quit then focus on the school.
No reasonable employer is going to expect a full time, long term worker while they are in high school. And the jobs wanting high school kids are also the type of jobs where job hopping doesn't really matter. As long as they get a few months use out of you, it's probably what they wanted anyways. More than that, they see it as extra scoops of ice cream.
you could do something "easy" and be a weekend aid at the hospital. Patient care/phlebotomist/etc doesn't require any special training, just a few hour classes. And they like weekend workers too. Not sure you could put in a few hours here and there though since they like having people for full shifts. But a full shift on a Saturday (leaving Sunday for family/homework) would probably net more money, and look better on a resume/college application. Doctors write great recommendations/references