Lumpectomy tomorrow - lobular cancer and so scared

Hello, I was diagnosed a couple of weeks ago with what looks to be invasive lobular cancer, and I am SCARED.  I meet with my surgeon this afternoon, and my lumpectomy is scheduled for tomorrow.  It was picked up almost accidentally on an ultrasound 7mm.  I have been reading lots and getting educated as much as possible, sometimes to my detriment, however I see an MRI is often recommended pre lumpectomy particularly for lobular cancers (as they are sneaky, and can often be in more than one place, or more than one breast).  However my surgeon says MRI is not necessary prior to surgery.  I will be meeting with him this afternoon to raise this issue of the MRI however the window for it to happen with surgery tomorrow will be difficult. 
Do I postpone my surgery and insist on an MRI?
I guess I will know more after my in person appointment today however I suppose i am wanting to know if many of you had an MRI as part of the pre-surgery process, to get a perhaps more informed picture of where things are at?
Thank you so much for any help and replies.  what a whirlwind this all is.