What test should I ask?

When I first diagnosed in Aug, the mammo and US found one tumor in right breast. I had bloody discharge that sent myself to dr. The surgeon told me I only have one tumor (mucinous and DCIS) and did lumpectomy and SNB. SN is clear but margin is not clear (showed DCIS). I insisted a BMX. so BMX one month later. Found I have multifocal mucinous and multifocal DCIS. Two days ago I was told I am also Her2+. After read posts on this forum and learn it is common for Her2+ to have multifocal tumors.

I also learned from some posts that for multifocal tumor, SNB may not be accurate. I will see my family doc next Monday. Am thinking to ask for MRI. Had requested when first diagnosed but refused by both family dr and surgeon as they thought US and mammo already caught my tumor. But apparent it is not the case.

I have done abdomen US and whole body bone scan. felt a little uncomfortable in right neck (maybe sitting and read too long at computer?). I am still worried about my lymp nodes. Hope they are clear as the surgeon has thought but I am not 100% sure. 

Should I ask for MRI or other test to further test lymp nodes? 

Sorry for the rant and thanks very much for your suggestions. 

Best wishes,

Meg