Hi, ebook addict. Love your name! I think it is good that they are sending you to a breast health center. They typically have the facilities to do a number of procedures there, so you will probably get quicker answers this way. I suspect your doctor told you they saw no microcalcifications, which, when clustered, can be an indication of DCIS, or ductal carcinoma in situ. These are usually seen on mammogram, and they look like salt sprinkled on the mammogram. The ultrasound usually is used to distinguish a fluid-filled cyst from a solid tumor when there is a suspicious area on the mammogram. It sounds like your doctor is determined to find out exactly what is going on, and that is a good thing. You are lucky!
When are you scheduled for your next tests? As far as should you be concerned, of course you should. You're 40 and you have 6 kids, and you don't know what is going on with your body! But try to save the worrying til you know whether or not there is something to worry about. If you have specific questions, we'd be happy to try to answer them. Let us know how it goes!
"There's a difference between a philosophy and a bumper sticker." --Charles Schulz