Does she turn around and lip your feet when you are sitting on her?
I am guessing she is just checking you out. Something that is not uncommon. And she has figured out how to make you go away and not ride her. Smart mare.
It sounds like you have made her work awfully hard since she has gotten to your place. Maybe a day with only one shorter ride would be best. She might be stiff and sore if your long rides 2x per day are more than she used to do at her old home.
As was said in the other thread. Getting yourself a trainer/instructor would help you tons. Questions like this could be asked of them, and their answers would be more spot on because they could actually see the behavior so they would more easily determine the cause and affect of the situation.
Have you talked with your parents about you taking lessons?