Visible Lump, but nothing on Ultrasound

I have a visible lump, on the inner under side of right breast. Can be seen and felt. Had an ultrasound today and although she could feel it, it didn’t even show up on the ultrasound. What could this mean? I have a follow up Tuesday with breast center. But feeling really nervous now. 

I could mean a number of things from your breast tissue being too dense, your breast being very large, or simply it’s nothing but normal breast tissue exactly like its surroundings. The breast center is the best possible place to get you answers and you don’t have to wait long to see them so try to hold till then. We all know the stress of waiting but truly the vast majority of lumps end up being nothing sinister.