Confused

I went to the doctors 3 weeks ago as I found a lump, the lump has been present over a month, I've been to the breast clinic several times due to my mum passing away from breast cancer. Each time I go I have an ultra sound and the all clear (thank god) I have been told I have extremely dense breast so I do know they can become lumpy. However this time was different, last week when I went to my appointment after my ultrasound I was asked to stay for a mammogram and biopsy, I knew it was different as they check under my arm pits. Anyways the doctor said he was sending me for an MRI... when seeing the consultant he said 'nothing is screaming out it's cancer but nothing is screaming out it isnt' ... now I'm just awaiting results but I'm really confused to the MRI as I assumed that is they was sitting on the fence then the biopsy would definitely tell wether it is/isn't cancer. Has anyone else experienced this or is this just an extra precautionary measure? 
 

thanks x