This is an interesting story and the beginning is very good. I also really liked her letter at the end.

Hmm...I think this would work better with other characters to be honest. It's a nice theme, but very modern in it's outlook, wording and setting. In the time of Rowena, the word trash didn't even exist and Helena would not have really associated with children in a neighbourhood as such. Pretty sure Slytherin was there when it opened and for some time afterwards as well.

Urgh, I feel like I'm giving you nonestop criticism. That's not my intent I assure you. It's sweet and decent.

Keep writing

*Gasp* Katie, this is BEAUTIFUL! I'm crying inside...
I love that last letter bit that you included; that was a definite bonus. This is beautiful! Thanks for writing this!