Puppy much younger than we were told

We adopted a chihuahua mix puppy from a rescue on 12/22. We were told she was 8 weeks old on 12/20. We moved last summer so we left our vet of 10 years and started going to a new vet closer to our home. We took her to her first few appointments with the new vet, but after a scary parasite incident and a trip to the emergency vet, we realized that the level of care just wasn’t good so we switched back to our old vet even though it’s much farther away. Our puppy just had her first check up with the old vet and, after looking at her teeth and the picture of the day she was taken into rescue (taken by police with her mother from squatter house), our vet (who I trust a lot) estimates she’s 3 weeks younger than the rescue was told by the police (the squatters told the police she was 5 weeks old). This scares me because that means we took her from her mother and brought her home at 5 weeks. She’s been the most difficult puppy I’ve ever raised and I guess that’s why. Does anyone know what things I can do now to fix whatever damage was done by that? We have her digestive issues straightened out with prescription GI puppy food. She’s nearly housebroken and interacts well with our 10 year old chi. She’s also very human friendly. She sleeps from 10:30-7:30 in a crate and we do enforced naps every few hours in her playpen with a crate attached. Bite inhibition is much better. She drew blood a lot up until about 2 – 3weeks ago. I’m just worried her beginnings might have messed her up. Has anyone raised a puppy this young? I feel like I should have known since she was sucking on my finger to sleep the first week and would route in my shirt and get frantic.