Haha, hilarious :D Now, I did like it, but prepare for some (lots) of constructive criticism! (Sorry, in advance)
You see, there were some really annoying mistakes... Or at least, really annoying for me, because I'm very easily annoyed by meaningless mistakes :P
Firstly: You say that her mum is 37 and had her at 19, making her eighteen, but that would mean she had finished Hogwarts. Her mum would have to be 35 for that to work :)
Secondly: To be an annoying Brit, the word "store" really grates as (and I assume you're American) we don't really say "store" :P it's normally shop :) I know it's just a tiny thing, but I'm annoyingly fastidious. Sorry!
Thirdly: I did like it, but the parents did feel a little forced and overexaggerated... Like the stuff about her being malnourished, and them smoking weed... It just makes the story less believable, you know? With the mistreatment you were describing there, social services would have definitely got involved! The bruises would normally be enough for most teachers to get worried - I went to a really rubbish primary school and the reception teachers talked to my parents and sister (and were prepared to take further steps) because she had lots of bruises because she liked to climb trees! So, while I understand why you want to have them be bad parents, I think that that is a bit too over the top, not to mention that, by law, sixteen year olds aren't allowed to be left for a whole night (let alone several days) with young children without adult supervision - the police would have got involved if it had have been reported, and I think that their neighbours really couldn't have managed to miss the parents absence, if their as loud, crazy and just plain worrying as you make out
Fourthly: With the weed thing... Basically I don't think that it's realistic, as babies who encounter drugs can experience serious side effects at birth (strong withdrawal symptoms) and would most definitely be taken away from the parents by the social services, who would be called in by hospital staff...
Sorry for coming along with a load of annoying laws and nitpicking!
Sorry again for all of the criticism though! Because, despite those things that I pointed out, I really liked your character's voice and the way that came through in the narration, while the plot line seems pretty interesting! The dialogue was generally great (although, is the brother supposed to be an actual "gangster" character? He more came across as a wannabe who wasnt doing so well) and although you could use some more, the description was good :)
So, sorry again for all of the major criticism, because I really did like it :D
Wow. That was long. *deep breaths*
Author's Response: Ah, thanks for helping me! I do need to know how to improve :)
1 - thanks, I hadn't done the maths. 2 - I am British, but I've read too many American fics of late! 3 and 4 - yes, I can see now that it is waaay over-done and unneeded. Everything's been edited accordingly, it definitely didn't need all of that! Thanks for making me edit, it needed it!
And thanks, yes, her brother was meant to come across like that.