I'm A Staff Member; I Should Know Better

I've worked my last day at the thrift store before I'm scheduled to go out of town this summer. I'm hoping to reclaim my spot in August, but I don't know if I will be able to or not. Part of it is because I made some mistakes in the last two days and am worried that I've messed up to the point where the manager may not want me back.

Mistake number one was made yesterday. Someone had come in with a bunch of donations. I was supposed to be one of the people helping get it in, but I had misunderstood the message that was originally relayed to me. By the time I did get to the back room, it had already been taken care of.  Still, I should have been fully aware of what was going on.

Mistake number two was made today. Someone came in to say that they had come to do community service, something I hadn't been trained to handle but apparently should've known the drill on. I called the manager to inform him, and his response was. "And?" (That's not the only time in my life when I've gotten such a response or something similar like, "What about it?" Those sorts of responses mean something like that what I had brought up was unimportant or stupid or it's something I should be able to deal with on my own or I had BETTER have a good reason for bringing up a single word of it.) I asked what it was I needed to have the person do, and he told me.   But it sounded to me like he was rather P.O.'d at me for bothering him over it in the first place. I feel so bad when I bother, upset, offend, or (fill in the blank here) someone who ranks above me in any capacity. When I go in to turn in my key (as I will be out of town until August, and something may happen that I will not be able to reclaim my spot), I may leave a note apologizing to the manager for bothering him over something that I should've known/fully figured out on my own. Such an action could work against my reclaiming my spot.

It's bad enough when I make mistakes as a daughter, sister, etc. (If you knew of half the mistakes I have made against my parents and/or sister, I'm afraid you wouldn't like me at all.) But making mistakes in a professional setting? That is just horrible. Four years ago, I worked at Burger King, and I lasted three weeks. Why? Because I wasn't fast enough to meet their standards. If only I had figured out how to get fast; then I wouldn't worry about the scarlet "F" on my work history, which could potentially work against my ever getting a full-time paid job anywhere. (After all, if I've let one previous employer down, what's to stop me from letting the next one down?) The thrift store position I have now is an unpaid one, but I still worry about messing up to the point where my being on the staff does more harm than good.

I hope I'll be allowed to reclaim my spot in August. If I am, then I will have to try extra hard to be the perfect employee who never makes mistakes. If not, and it's on account of mistakes I've made, then I'll be lucky if I don't end up shunned by the entire job market, something that could make me a disgrace to my family and possibly all of humanity, and I don't want that. But short of asking God almighty to help me stop making mistakes, I don't know what else to do.