US and mam of bi-rad4c, worried!!??

I noticed a very large left breast lump last December that is actually 4cm. I had a normal OB exam in October with no lump. As far as I know, the lump remained the same size since I found it. I finally decided to get it checked out because it started to bother me. I occasionally have some pain or tenderness and minor itching but nothing is consistent. So far I've had a mammogram and ultrasound. By the way I'm only 37 with no family history of breast cancer and I have two little kids... Fairly healthy... No one really talked to me after my mam or ultrasound. The techs just kept asking me if I had an injury to the breast which I said no. They also just told me I need to schedule a biopsy which is for Thursday. I got my results online through my medical chart... The nurse practitioner I see at my OB didn't have a lot to say except it's good that I went in. I'm basically convincing myself I have metastatic cancer. I'm freaking out!! Like I was getting at, my results didn't say much. Just that I have heterogeneous dense breasts, I was rated a bi rads 4c which I've read is not good at all. The results also said the size (didn't say anything about shapes or borders), said it's hypoechoic, which I read means it's solid... On palpation it does feel big, hard, and moveable. Results also said breast has calcifications and punctate echoic foci and that there is not any architectural distortion in either breast. My results didn't say anything else except all of that. I never got to see pictures of the mam or ultrasound... Can someone please help ease my mind??