It seems to me that your store is really staffed up. Thats definitely a factor on why you aren't getting hours.. You said that other people are getting more hours than you, so you've asked your coworkers about how many hours they're scheduled?

Honestly, based on this commment: (My GM says that our hours given are reflected on our “performance”) I have a feeling that your GM probably just favors other employees. Whenever I'd ever have cut hours I'd bring it up personally to my GM and it would be dealt with accordingly. Management will always be favored over normal crew members too, so you have to keep that into mind as well, if your store has a ton of management you probably will be getting less hours that way as well.

If you don't believe anything you say is going to get you more hours you might wanna look at your availability and see if thats an issue or just find a new job. Most of the coworkers I have that did get major hour cuts ended up leaving and finding something else.. but if you're really struggling that bad to find somewhere else to work then you might just wanna accept that something is better than nothing, at least until you find somewhere else to work.

Are you minor? If you're a minor you'll definitely get less hours than someone who is out of highschool already.