I go through this every couple of years. I come from a long family history of breast cancer, and every little blip, lump, or bump gets the "it might be cancer" treatment. I know it is incredibly stressful, and no one will handle it the same. Here is my advice:
Stay busy and TRY to not dwell on it. (Easier said than done, but if you do something you really love, spend time with people you love and enjoy, it really does make a difference!) Realize that your worry will not change anything. It does nothing but drain you and make you miserable! Also realize that the doctor said might....it is not a diagnosis. And lastly.... remember that you have a Lord and Savior that gave his life for you. He loves you and will give you the strength and grace to face whatever tomorrow may hold!!
You will be in my prayers!
P.S. Cut your mom some slack. She is your mom, she loves you, and wants to protect you, and she is probably doing the only thing that she knows to try and help you and try to deal with this herself. Health scares like this affect everyone in the family, not just the one with the issue. If it is driving you nuts, tell her calmly and respectfully what she can do to help you through this.