- Is this the first time a lump has been detected in one of your breasts?
- Have any of your first-degree relatives have breast or ovarian cancer?
- Were you over the age of thirty when you had your daughter, and did you breastfeed?
Some of these things present risk cancers for breast cancer developing later in life. You're quite young to have breast cancer, unless there's a history of early-onset (before age 50) of breast or ovarian cancers in your family (even then, you'd still be considered young, though it can strike in your twenties, in very rare cases).
The survival rate that you've quoted is actually a very good one. It doesn't mean that you'll die when you hit the five year expiry date - it means that 85% of breast cancer patients live at least five years after their diagnosis. Breast cancer is treatable if it's detected early.
My mother died of breast cancer after one hell of a long struggle with it. She just flat out refused to die (until she did die, obviously). I'm not sure what you mean when you ask "what were their symptoms before they died...." Most people who're about to die - of anything - have basically the same appearance because the physiological problem - imminent death - is exactly the same, and I assume you want to know what you'd be looking like if you were about to die in, say, a month. It's extremely unlikely that you'd die within a month.
I personally hope you don't have cancer. I have known many other women who have had breast cancer and who've survived it, so if it does turn out that you do have cancer, attend to it immediately, follow doctor's orders, try to remain positive and hopeful. Good luck.