Crying and then jumping and attacking me

Hi everyone!
First time Staffy owner here. My boyfriend and I recently got a beautiful blue am-staff x bull arab from a shelter. She is 10 months old and her name is Dior. We’ve had her for 3 days now and she’s been an absolute handful. Somehow (I think) she’s bonded to my boyfriend intensely and me a little bit. Every time she sees my boyfriend leave the house or closes the door to go to the bathroom, she will jump up and push against the door and cry and I keep telling her it’s okay but she turns around and will jump at me and show teeth (super scary considering I’m a small girl lol). It sounds like she’s under extreme distress but she gets like that even when I’m still in the room with her. We haven’t been able to start training her to be all by herself because we can’t get over this obstacle. She weighs 26kgs so having her jump on me and biting me when she’s upset is definitely not ideal. She’s still technically a puppy as well and it doesn’t sound like the previous owners trained her at all. I have to keep her distracted with bones she can chew on and get her to walk around with me or else she’ll get fired up again and come at me. She hasn’t bitten me yet and I don’t want her to considering Staffies tend to lock jaw. I don’t want her to keep this attitude/habit. Please give share any sort of advice you can. I love her already and don’t want to be scared everytime my boyfriend leaves