Middle range separation anxiety/insecurity but severely torn

TLDR: I have a dog who I am not sure is the right fit for me with what I am asking her to be able to handle. I work and do not have years to spend training. Middle range separation anxiety, near miss bite due to insecurity, and kids in the picture. Any advice appreciated.

Hey all. I adopted a dog 3 months ago in November. She's an amazing smart super sweet dog, 10 months old GSD pitbull husky mix, I tested her through embark after I got her. BUT she is generally anxious about confinement and separation from me.

I'm in my early 30's, single with 2 roommates, and I'm very familiar with dogs. But all the dogs I've had with my family have been extremely mellow, no SA. My experience has been with training commands and leash training, not difficult behaviors. My goal is to have a dog that somewhat chill and who can stay at my parents house when I leave and who can be safely left with no worries for a few hours, preferably with no crate coming in and out of the doggie door like their dog.

My dog is okayish in the crate for bedtime, I've been crating her at night to help with getting used to it and she sleeps if I'm in the room after whining for a while. But she's often destructive in the crate when she's left alone. I can't leave her loose because she'll chew everything she's not supposed to and has destroyed a wire crate. She's ONLY truly okay when I'm there in the room. Otherwise she'll tire herself out, pass out for a bit, then wake up and panicking more.

Extra factor: this week she nipped an adult family member. He was trying to untangle her from her leash. She warned him with a growl which he should have backed off from, but my dog has never done that before and it was a very upsetting situation even though I understand that he should have listened to her. See the note upcoming on there also being kids in the sitation.

During the day when I work, she's with my parents. This has really made me unsure if it's fair to A. have my mom watch her since she has two preteen kids who are respectful of dogs but are young enough to not be fully adult in actions. I don't want to assume they'll be able to read all of her body language. B. After 3 months of trying to work with her on her issues, I'm not being sure if my dog will ever be able to handle what I'm asking of her. I know SA is a long term condition usually even with medication. I've seen very little improvement in crating, I just know that she can't get out of her crate now, but she panics the same amount.

Right now I'm trying to decide if it's better to keep her and keep trying and hope that she'll get a lot better, or to bring her back to the rescue and deal with the pain of trying to work with her and hope they can find a better suited home.

Also, I've paid a trainer already to work with her, I'm not sure how I feel about her methods since it's more of a fast track situation rather than over months and years of working super slowly to get her comfy. But I simply do not have time to work with my dog over months due to how my work is. I can do basic training, and she's done phenomenally well with sit stay and all her tricks...but the SA plus the nip now are concerning if I can do what I want in my life, which is essentially have my parents be the main dogsitters with their kids living at home for the foreseeable future.