What should I do about my job? (sorry it's so long)?

It seems like you have (or at least had) a good relationship with the couple who owns it... can you talk to them? Let them know what's going on, that you're trying your hardest. Tell them if they have any suggestions to let you know, but that you're worried you might make mistakes.They sound like nice people, so I'm sure if you just talk to them they'll try to help you out.