Basically, she is asking for a quick overview of your life and stuff. Very quick, mind you. A sentence or less. E.g. "Yeah, I'm good thank you, school has been intense but I finally understand pre-emptive conjunctions now. How are you doing?"

I got the message from my teacher whom I haven't seen for a long time and I don't know what to say to her.. I want to reply in shot (?) but in detail in good English. [I'm a university student] The answer to the question "how's it going" is usually, "it's going good"...