Hi,
There is a lot of info on the web regarding your questions.
You asked the difference between er/pr neg, and er/pr pos.
Whether or not there are estrogen and progesterone receptors with the cancer cells. This determines whether the treatment you'll receive is hormone based or not.
Lymph node involvement does not mean metestatic bc. It means that there are cancer cells detected within those lymph nodes, it does not mean that there is cancer elsewhere in your body.
The accuracy of HER2 diagnosis was well answered by Tousled1 (Kate).
Welcome here, We have found some of the best people... very warm and caring souls who are full of information and compassion. Some answered you already! We are new to this too, and we thank you for being here.
and yes... this dx of HER2 is not what it once was. There is reason to think it is the most treatable of cancers now.