Stage 2 is better than stage 3 and 4, so you have a very good chance of non reoccurrence. Hopefully you will be able to continue with the herceptin which is a great medicine for Her2 Positive. There are various websites giving information on reoccurrence but to be honest I found them very confusing and at odds with each other. The best source for information is your Oncologist. He/She will only be able to give you the general statistics for your cancer diagnosis. The grade of the cancer is important, your age, your menopausal status and very importantly your state of mind. A positive outlook is so important. I know it is very hard to be positive all the time, I have my up days and down days. I wish you all the best with your future and I do hope you will remain cancer free.
Whenever the cancer occurs at the same site as that of the original tumor, it is labeled as recurrence and when it occurs at other sites such as nodes or distant organs, it is termed as metastasis. The risk of developing recurrence / metastasis depends on various factors. (E.g. histopathology report) The outcome following recurrence is generally thought to be incurable despite aggressive approaches.