Gahh please help..? Advice?

I might be overthinking it, but I'm honestly not sure. So I got a part time job a year before I started college. It is one evening and weekends, so it sounds like a job given to students of course. The only thing is, it's a small job. Meaning there are only 4 of us employees total. I have school in the middle of the day every day, except friday where I'd be able to come in if I was called in, but still not until noon. I'm just afraid they might want to let me go now that I am in college and may not be able to come in if someone else can't come into their shift. I can always go into my own, I just almost never can cover for anyone else anymore.