Because her bond with her family was almost lost as they were unable to help her back then.
When a different factor entered the equation she created for herself, she started getting lost in her own maze.
She was intelligent and capable. The only problem is she is too emotionally damaged.
"So why don't you start now? Start by telling me what you truly are hiding. The things you did up to now, I had been having the feeling that you had seen the future."
Wesley didn't go in a round about manner. He chose to go straight to the point.
And Heather who became emotionally vulnerable couldn't stop herself from looking shock at his question.
Her reaction instantly allowed Wesley to know that he was right with his assumption. Heather actually knew the future.
To be honest, he had been denying this because it felt surreal but everything was already laid down in front of him.
Heather had done so much that points to this reasoning.