Have lump and worried!

At my annual last year the dr found a lump on the outer part of my left breast. It feels like a rubbery jelly belly jelly bean...shape. You can kinda move it around. My dr ordered a mamo and when I went to the hospital to have that done the radiologist said to do an ultrasound...so he had the order changed and did the ultrasound. They could not see it on the ultrasound so said that most likely it was nothing. When I got home I had a message on the answering machine to come back do to the mamo. I went the next day and had the mamo done which again...showed nothing. He said that because I am so young that my breast tissue is very dense. At my follow up appt my dr told me to have an ultrasound done every 6 months and to call immediately if anything changed. I had another ultrasound done 6 months later by the radiologist. He said that he could see it and they measured it and everything and said that it was nothing...I forgot the term he used. My mom has had several benign lumps removed and I have no other family history. It has been almost a year and still no change. I am going to see a surgeon tomorrow to get another opinion. I just want to be 100% sure.
Any suggestions? Am I doing what I need to be doing?
Thanks!

My surgeon seemed a little concerned so he sent me to the hospital for an ultrasound. The tech could feel the lump but couldn't find it on the screen so she had she radiologist come in. He did the ultrasound and said that it was normal breast tissue. He said not to worry about it and to only check it once a month. He said that he did not see any reason to have it removed but to follow up with my surgeon. I have a follow up appointment on May 4th.