My wife had breast cancer and hers was HER2 (She's only 34). She had lump in her breast and when she had a ultrasound it came back as a cyst, she asked for a mammogram and it came back fine. She then demanded another scan with a different nurse, they found they cancer hiding behind the cyst. I would ask for another opinion personally, another mammogram and ultrasound. If it wasn't for the nurse who found the cancer behind the cyst, it would have been a  different scenario alltogether.

This is your health and your body, you have every right to ask for another opinion. My wife new deep down something is wrong. Go with your gut.

I really do hope you get some answers but don't feel bad for asking again, it's your health at the end of the day.

Kind Regards,

Dave

Sorry to add, but you should ask for a biopsy, better for your own mental health also to rule it out. 

I hope it turns out to be nothing but better to be safe.

Kind regards,

Dave

Sorry to add, but you should ask for a biopsy, better for your own mental health also to rule it out. 

I hope it turns out to be nothing but better to be safe.

Kind regards,

Dave