You think too much. There are many possibilities for the other party to add WeChat delay. For example, although she has a micro-signal, she seldom uses it, so she can't see your application, or she rarely adds various applicants, usually only adds her own good friends, or she seldom uses WeChat recently, so she can't see your application. ...

Go to your class as usual, she may not even know that you applied to add her. When you come near, you can ask her if you can add her.