1) The nature of this document is a personal diary held by a young Mexican girl.
2) Her family is formed by her two parents ("Mamá" & "Papá") and her five brothers: Mario, Victor, Hector, Raul, and Sergio.
"They" (l.3) refers to her parents. "we" (l.3) and "our" (l.3 + 4) refer to her whole family.
3) When it was time for bed, the girl didn't directly fall asleep, that's why she was able to hear her parents having a conversation about their family possibly moving out to LA. Knowing that, she couldn't sleep anymore and this is what has led her to write this note on her diary.
4) The narrator feels crushed because such a change in her environment isn't easy to deal with. She has lived her entire life in Mexico, and going all of a sudden into a complete different place can be quite scary. She also feels incomprehension towards her parents decision, which feeds even more her fear and her inablity to sleep at the moment.
