I have been in your situation, and it is very hard not to think about the possibility of it being cancer.
I am glad your already scheduled for US. If needed, the next step would be a biopsy and ask about a breast MRI . In my case, insurance would not pay for MRI till there was a confirmed case of breast cancer.
There is not much you can do till have results. If it is cancer, then it becomes many appointments and discussions. Take it one step at a time.
If your biopsy is positive, there has been discussion topics on questions for provider,
It might be a good time to start a journal and log of activates. I normally do not journal, but did after diagnosis. It was good way to write down all the feelings your having.