You are what I care about. You are what I miss and miss.

As for how to reply, it depends on whether you are interested in her.

But I can't know who she is in a whisper.

You can go back like this:

Qing is what I think and Qing is what I remember. Today is the right time. Would you rather have one side?

It means:

You are what I miss, and you are what I remember. Today is a good time. Can we meet?

This will expose her identity, and if it happens to be someone you like, you can also ask her out.