I love the halti. I use haltis and gentle leaders on my dogs, but they have to be trained to willingly accept them. Some dogs will freak out if you just stick them on. I had my dogs wearing them from a very young age, so they got used to them just like a collar.
If she's doing good with the harness and is comfortable in it I'd just stick with that.
Next time you take her to the vet try giving her a bunch of treats so she looks foward to going there. Every time my dogs go to the vet the vets always give them lots of attention and treats so they're excited to go.
I'm surprised the nurse described your puppy as aggressive. It sounds like maybe she's not that comfortable with dogs, which is odd for a vet tech, so I'm sure she gave your dog a bad experience, being uncomfortable and all.
The pulling on the clothes thing will just take time. You think your puppy is bad, trying breaking a herding breed of that
. They LOVE to chase stuff and nip and grab at ankles and clothes. When walnut was little I swear I had puncture wounds all over my ankles for awhile from her nipping. Once she learned it wasn't ok and got older she never even nipped anyone at any time. Little kids would run up to her and hug her and she'd just sit there. She could see little kids running around and just follow them without nipping or trying to herd.
I kind of wonder if the growling isn't just vocalization. Is there any way you can take video? Some puppies can seem very aggressive when they're just trying to be vocal and communicate. Malamutes especially are like this. I have a little half malamute puppy right now, and her and her sister growl CONSTANTLY, which seems aggressive to some people but it's just the way they talk. My puppy's sister runs around making growling noises loudly and it sounds very vicious, but she intends no aggression at all. They're also very nippy, which we're working on breaking.
Not sure if vislas tend to be vocalizers because I'm not familiar with the breed, but even if they aren't I'm sure some individuals can be.