I also had your same opinion, my breasts were so lumpy that I couldn't tell one lump from the other. My mammograms were as white as a newly laundered sheet. The thing that docs want you to notice is.... do the lumps change????? That is the big question. If you feel ANYTHING different in the lumps, and trust me, you'll know different when you feel it. Get to know your lumps, love your lumps. Do the self-exam. You are the first one to know when something is different. Even if you are wrong, let someone know. Then you'll know what's now normal FOR YOU.
Did you request a copy of your ultrasound results? If not, do so. See what the radiologist recommended. Ask what your BiRad rate was on the ultrasound. If you are still concerned, get a second opinion. Good doctors welcome second opinions.
Consider asking the doctor to put in a mammogram for your peace of mind. The radiologist can compare it to the ultrasound. Cystic breast mams are hard to read though. If your mom had BC, the doctor should be more proactive for you. God Bless