For 11 this is ok, I wouldn't really expect much more out of you, but if you want my honest opinion this is pretty bad.
For one, go back and try to find the points where you repeat yourself, you do that a lot. Word choice is also important, as a lot of the time you repeat the same word twice in a sentence, or use very poor words. Vocabulary is a big part in writing.
The story line is also very undeveloped and random, at one point your describing everything around you and then you somehow muster up the strength to run outside for now reason with your sister (who by the way is a completely unbelievable character and you should think of re-doing her).
The story itself is reading like a train of thought, like you have all these ideas and you just slap them down on the paper without any proofreading or anything. At one point (my quotes could be off), you say "I saw my mother on the ground blah blah..." and then right after that you say something similar to "I finally gained the strength to open one eye". How would you see your mother unless you already had your eyes open?
Overall just re-read it over and see how nearly every paragraph repeats points over or has other very large faults.
