Advice on my job and looking for new jobs!!🥴🤬🥶

I am 17 and work for a law firm as a courier. I haven’t even been there for a year and I am fed up and just need to quit right now. I feel like I try to do my best with the time I’m given but it’s just not working. I normally go into work at 2 and we close at 5. I leave for runs at 3:30 everyday, or at least try to. Most of the times I am unable to leave until 4 because everyone does everything last minute and makes me wait. One day I didn’t get to leave until 4:20 and could only do half my runs because everyone wanted last minute shit to go out. Another day a lady asks me to do something, which I wrote down right after she asked me and did it. Then she texts me when I’m in school and says she didn’t ask me to do that and instead asked me to do something else, but I know she’s lying because I wrote it down right after she asked. They then tried to blame mail being mailed without postage, which I double check for postage when I leave and when I get to the post office, I’ve even came back to the office to put postage on mail when I forgot, so I know I did not mail anything without postage. They also tried to blame late documents on me when they messed them up in the first place. The check was short for it to be recorded and the recording office takes forever to return documents, so I don’t understand how that’s possibly my fault. I have to do dishes in the office, which for one I don’t understand why they can’t wash their own dishes, but when I left at 4:20 that day I obviously didn’t get back until 5, so my coworker decided to help me out and do the dishes for me before she left because I wasn’t back yet, and she said out boss got rude with her and was like well she should have done them before she left that’s her job. Mind you I do the dishes at the end of the day because they pile up and I’m not washing dishes twice a day. I never get told anything about what I’m taking, which makes it hard to do my job correctly when I’m asked questions about what I need, and if I ask them they get snappy and like I’m making them work more. I’ve been looking for another job but haven’t had any luck and I need to find another job before I just quit and have no job🙄