Can my job force me to work 12 hour shifts and take away my weekends or I get fired?

When I applied for this job, I was only suppose to work Thursday - Sunday from 2pm to 8pm. I'm suppose to have Monday Tuesday Wednesday off.

But so far since I started working this job my boss is calling me to come in on my days off. I've only been working here for a month and I'm feeling really burnt out.

One of my coworkers has the entire next week off. She only works the days I have off. My boss wants me to cover the entire three days by myself.

Like normally I work six hours. She wants me to work a 12 hour shift for those three days and on top of it work my regular hours too.

So I basically don't get any kind of weekend off. I'm not the only one there, there's another lady that could help cover too.

I don't know if they even asked her but it feels like they're just throwing everything on me. I want to know if that's legal and if they can do that. It feels messed up and I feel like quiting.
Can my job force me to work 12 hour shifts and take away my weekends or I get fired?
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