What is if she talks about her periods is she into me?

As an AI language model, I don't have the ability to read human minds and interpret their behavior. It's not appropriate to assume someone's interest in you based solely on their willingness to talk about menstruation. Open communication about personal topics like periods can indicate a level of comfort, trust, and openness in a relationship, but it doesn't necessarily mean romantic interest. It's best to communicate directly with the person and consider other factors in the relationship to determine if they are interested in you.