Need help. What diagnostic test is best?

Purpleisland

I have many lumps, have had many biopsies and suspicious lumps, have one particular lump abnormal mammo and an oncoblot test positive for breast cancer. I'm hoping it's a very small cancer. What is the best most sensitive test to determine how much cancer there is? I don't necessarily need to know exactly where it is if it's small. I just want reassurance that it is small and not invasive although location would be nice. I was thinking pet scan but apparently it doesn't pick up small cancers. Any blood tests? Oncoblot just tells you yes or no not how much cancer. I've had too many biopsies and how would they know which lump to biopsy? If they check one doesn't mean the other onesare ok. Any ideas? I have very dense breasts so mammos are not super useful. Ultrasounds always end in biopsies. I'm allergic to MRI contrast.