HI and welcome to YT. First, congratulations on your addition.
Secondly, it sounds as though you were given quite a story about what Bella. I would say have some patience with her and give her ample space to adjust to her new home. Her world, as terrible it sounds to be (imo) has been turned upside down. She's only known how her previous owner has treated her. She needs to learn that you will treat her differently and more lovingly.
Third, try not to introduce too many new things to her right away. She's probably very confused and scared. As for potty training, have you considered an expen? You can have her crate, toys, potty pad, food and water in there so she can have some room to play and roam. I personally do not like crates but they do serve a purpose. I chose to have an expen. I think it's a much better alternative.
Yorkies are very difficult to potty train. You will need patience and consistency. She will learn but may have a few accidents. Did I mention that you will need patience? lol
Good luck and Bella will surprise you if you just relax with her, she is only 7 mos old. Yorkies are very smart. Have you started any type of training, tricks with her? She may respond to positive reinforcement of treats or praise much more quickly.