[TOMT][SHORT STORY] about a young woman who is appalled by people erasing their memories, only to discover that she has erased her own memories in the past

Hello everyone. I'm looking for a short story that I read when I was in 7th or 8th grade. It would have been around 2000. In the story, the female protagonist, and her friend (a boy), live in a future where it is possible to erase your memories. The young woman finds this horrible, as does her friend. I seem to recall that near the beginning of the story, her teacher had erased a memory of someone? The young woman decides that she is going to access a database with records of everyone that has erased a memory. When she does, she discovers that she had erased all memories of her dead sister, then erased the memory of having erased the memory. She is devastated and decides to erase all of her memories. The story ends with the friend finding the main character, who has basically reverted to being a baby, but in a young adult's body.

Anyone know what I'm talking about?