Would you be mad?

Alright, so I have 2 other coworkers ( we will call one Baylee and the other Lacey) and this month Baylee is only getting 5 days worth of work and Lacey is only getting 4. I work the rest of the days besides Sundays we are closed. My total hours for the month is 127.50. I won't be able to call in sick or anything because there will be no one to cover me. Lacey with her scholarship can only work 9 hours a week because our job is through the University. Baylee has another job that she works so when she isn't at this one she is there or on vacation. I swear she takes a vacation every month. I am upset because they schedule me like this, but won't just hire me full or 3/4 time because they don't "want to cover me with insurance". Last week I also ended up being forced to stay a hour after work because my manager ran into a problem and wouldn't let me leave, but also said I wasn't allowed to write down the extra hour! So I don't even get paid that overtime. It's such bullshit. Would you quit?! Should I quit?!