It sounds like she's experiencing reactivity due to fear. She's been through a tough time. My little guy is a bit reactive and snaps at other dogs, but has never actually bit. My thoughts are that you need to not punish her for defending herself, but re-direct her attention to something positive and reward her for being calm. It may be as simple as walking somewhere where other dogs are not present until she is more used to you.
When a dog approaches you, inform them that she is rescue and is reactive, then if they approach too close and your dog bites theirs, it's their fault for not listening. On your side, when a dog approaches use a toy or treats to redirect her away from the approaching dog, use your body to block the other dog, possibly ask for a sit or something and reward her every time she looks at the other dog without growling or barking or snapping.
I've gained ALOT of progress with this cause if you punish a reaction based on fear, you are just creating more fear, essentially making the reaction worse next time. You want her to enjoy meeting dogs, people etc. So make it fun for her. If people approach her on the street a good trick to keep people at a distance is ask them if they want to see a trick (this means you need to teach her some
) so then they step back to watch this awesome and adorable trick, allowing you to reward your dog at a distance and assure that she doesn't get upset with the passerby.
Also with Maya, it could just take time. I wouldn't punish Bella for annoying Maya, but your job is to supervise them and if you see inappropriate body language, just step in and remove Bella calmly, when she calms down release her again, and have someone praise Maya. When Bella plays nicely with Maya, then you need to praise her and let her know that's the appropriate way to play. Also Maya may actually be teaching Bella. I know Harley HATES puppies, and he teaches mom's beagle puppy Duke how to play properly. If Duke behaves Harley is nice. If Duke plays too rough he bares his teeth and play bows and tells him to back off, then chases him. If you watch them interact watch Maya, is her tail wagging? If so she could just be playing with Bella in her way. If the tail is between her legs, then remove Maya she's stressed. If her ears are ahead, she's attentive and happy, but if they are pinned she's mad. Is she hiding or is she engaging in a "fight" with Bella. These are all things to watch for.
Sorry for the big book. lol. Hope at least some of it is useful,