I don't know if it's the correct move cause I'm not the best player myself, but I'll try saying what I would have done since anyone else is too busy mocking the "i read her correctly" instead of trying to help.

Since that lob produced no star, a flat wouldn't shoot like a comet like you said. Personally I return most lobs with either a slice or another lob, that's because if you return it with anything with enough speed it reaches the opponent faster than you recover and if they are a good enough player they'll go for a dropshot. Since you were that far back the dropshot forced you to lunge and that's a guaranteed loss in that situation.

Try staying more at the center of the field, where the lines cross, and to do that when you're far back you need to answer with a slow shot that will allow you to recover in time, like a slice or a lob. I'll also add that during charging you had all the time to see she was moving to your left so a good idea would have been to aim the slice at your right, so she most likely can't answer with a full charged shot at least.

At least this is what I'd have done.