Small lump that can be felt but not seen on imaging

A few weeks ago, I found a small lump in my breast just above lumpectomy scar. I had a mammo and ultrasound at my GP office. They could not see anything on mammo or ultrasound, but because of my history the recommendation was to see a surgeon for a biopsy. I was given the choice of meeting with a general surgeon in town or being referred to a breast specialist in a bigger city an hour from my home. I decided the smartest move was to see a breast specialist who deals only with breasts every single day. Fast forward a week...

So Thursday I went to a highly reputable cancer facility an hour from my home. I met with a breast surgical oncologist fully expecting to have a biopsy. She reviewed my history with me, examined my films and prior pathology. She was able to feel the lump and said it was very small. She also preceded to tell me that based on my previous diagnosis and treatment there was only a 5% chance of a recurrence of breast cancer in that breast. She mentioned also that she really didi not see anything alarming in my mammo and ultrasound, but wanted me to have a repeat ultrasound in their facility because she had a tremendous amount of confidence in their technicians and radiologists who deal with breast issues on a daily basis and have seen everything imaginable.If anything suspicious showed up, I was to have a biospy immediately. I had the ultrasound and liked the technician who performed it. She was very open with me and explained everything she was doing and what she was looking for. We marked with a pen where we felt the lump and had the ultrasound. She found nothing at all suspicious. I asked her if that was a good thing or a bad thing. She said that was a good thing. She showed the films to the radiologist who also came in and said she saw nothing worrisome, but she was going to just double check herself. She also felt the small lump. She explained to me that among other things they look for increased blood flow in the area and she saw nothing like that going on. She couldn't get the lump to show up on ultrasound either and did not recommend a biopsy. When I asked her what she thought the lump was then she explained that she felt it was a pseudo lump (normal breast tissue). The recommendation was a six month follow up with mammo, ultrasound and visit with the surgical oncologist. No mention of an MRI and I did not think to ask for one at the time. I was so relieved with their recommendations. But, now I am wondering if I should have asked for one or why they didn't suggest one. Am I worrying needlessly? These are people who deal with breast cancer on a daily basis. Wouldn't they be extra cautious with someone who already had a history of bc? Leave it to me to worry about a 5% recurrence chance instead of focusing on the fact that there is a 95% chance that I have absolutely nothing wrong with me. Grrr! Not sure if I should call back and ask questions or put it out of my head for 6 mths and enjoy life.