This is where it gets into irrational concerns. In most locations, reusing needles is not practice or something anywhere would do. There is a virus these days called corona virus which if you have a fever, you should talk to your doctor about that. This is the times of a global pandemic so it would make sense to be evaluated if you have any symptoms of that. But this is not an hiv concern as your anxiety is playing tricks on you.
The only non sex risk for hiv is sharing hollow needles that you use to inject with so there is no hiv risk from a blood test anyway.
You watched her open a new syringe so I don't know why you think she did not use it. You describe all of your "symptoms" as slight, which might be because they are in your imagination from fear. Your claim of fever for instance, is normal temperature.
hiv doctors can't diagnose from symptoms and only rely on test results so no one here pays attention to symptoms and you shouldn't be wasting your time doing "symptom" analysis for hiv either because it will not work. If you are sick see a doctor but it isn't hiv- first you should stop worrying, stop Googling hiv, and stop analyzing your body for one day - If the symptoms disappear then they are in your imagination from fear so you should stop doing those things that make you afraid.