Knockout wrote:
I definitely will keep on top of it for myself, since it's pretty much guaranteed that I will get it now...

And I will do my best with support, I just hope she takes it as me caring and not as me just saying things...
This is NOT true! Please don't worry yourself unnecessarily.

IF your mom does actually have one of the BRCA mutations, you have only a 50% chance of having inherited it from her. BRCA usually also presents in families as ovarian cancer, so unless your grandma's sisters and your aunts also had a high rate of early breast or ovarian cancers, it is not very likely.

That said, once things have settled down with your mom's situation, you should consider seeing a genetic counselor to talk about your risk profile and what kind of genetic testing may be appropriate for your family. That will help you and your doctor decide what kind of testing and monitoring  you should do in the future.

Unfortunately, breast cancer is very common, and you don't have to have a "family history" to be at risk. But you should also not consider yourself "doomed" to having it!

BTW, if your mom has ductal carcinoma in situ (my guess from what you said) it IS very treatable and the prognosis is very good!