Sorry this is causing you so much stress.
It can be so many things that are so trivial..for example..they may need another picture because the one you took may not have come out right, they may be looking at a cyst and want a closer picture. you may have dense tissue and they need a higher resolution..If you had anything that looked suspicious, you would have received a call from the radiologist.
Please do not worry..I have a family history and I always have additional testing done, which is usually just an ultrasound.
Good luck and let us know what the doctor says.