I am really a super sensitive person. For example, if I send a text message to my classmate and she doesn't reply to me, I will wonder if she hates me. Well, how can we do that? ...

Your sensitivity actually reflects from the side that you are a person who cares about other people's opinions. Care more about other people's thoughts and feelings, so when you encounter this situation, you are willing to worry about whether you have done something wrong, but this is actually a good quality. Communication is the most important thing. If you have any questions, just say it.