You could just have genetic counseling first. They would review your family history and tell you if they considered you a good candidate for genetic testing. They would also tell you who in your family is the best candidate for the testing. I waited a number of years after diagnosis before undergoing testing. Even though I had lost my mother and three aunts to cancer, my daughters were young and I didn't want them growing up knowing they were likely to develop cancer themselves. But when my brother was diagnosed with prostate cancer, I talked to my daughters (grown my then), and they both wanted me to have the testing done. The geneticists considered me the best candidate in our damaged tree for testing, so I had the tests for BRCA I and II, and both were negative. Had I been positive, my children and niece and nephew would have been much easier to test, because they would have known specifically where to look for the genetic markers, based on my test, ergo, their testing would have been much less expensive.
A negative test is not a guarantee that you do not have a genetic marker for breast cancer. There are other genes that are closely related to breast cancer that can be tested, but aren't done by computer, so they are cost prohibitive to test for (P53, for example). Also, the mutation may be so extreme that the computers don't "read" it as an abnormality (computers can only look for something they are programmed to look for).
Because you have not actually been diagnosed, your mother may be the best candidate for testing. But that is what genetic counseling is all about, and it is relatively inexpensive.
Good luck. (How is your mother doing, by the way???)