It sounds like you are snapping. Usually I begin to notice behavior patterns when they are already in full swing. Consider weight changes, loss of interest (cooking), increased exhaustion, and being completely overwhelmed with getting out of bed. It sounds like (to me) you might already be depressed.

How long have you been at this job? A reduction in hours might help -- remember don't feel bad for the managers for taking on the extra duties of training someone and filling the hours.. You need to worry about you, especially if you are snapping. If you reduce your hours, would that be a financial risk? Do you think it's the field of work you are in? I thought retail was completely awful and hated every minute of it. I worked slowly but surely on getting out.. Even looking at your resume or looking at other jobs and possibilities might make a difference.

However, if you are struggling to get out of bed and struggling to live at a bare minimum, you should consider talking to someone (doctor, friends, whoever). Remember you are not in a "box".. you are not stuck at this job or in retail or this life situation forever.

I hope you feel better. Retail is notoriously mentally and physically taxing with no sort of compensation in the actual work you do. I don't think it's worth it (for me). Sure, I liked talking to customers and helping them out, but it's not worth the shallow hourly rate or the toll it takes on you.