Hi Dylan, Welcome to the forum 😊
Firstly yes definately take someone with you to your appointment, a second pair of ears is invaluable as you just can't take it all in yourself and I also found my husband spoke up and asked the things I said I wanted to but had completely forgotten to say on the day.
DCIS can be wide spread across your breast so sometimes a mastectomy is needed to remove it all but it varies and everyone's case is different so you can't read too much in to what others have had done.
Margins refer to removing the cancer with a few mm of clear tissue surrounding it, sometimes they don't achieve this first time so a second surgery is done to remove some more, again this doesn't happen to everyone so dont assume if you have a lumpectomy it will to you.
A marker is sometimes put in to a lump at point of biopsy purely so it's easy to find if it needs removing , I had a guide wire inserted via ultrasound on the day of my op.
At your appointment your team will talk you through what will happen next but question anything you don't understand, you can sit there like a rabbit caught in headlights then come away kicking yourself for not asking more. Get someone with you to right it down and ask for clarification on things you don't understand.
They cant give you a definite Diagnosis at this stage until your DCIS has been removed and analysed further so there will be more waiting but they will tell you what they know from your biopsy.
Questions to ask include what size, type and grade they think it is, will there be further tests i.e. scans or MRI, what will the likely treatment be and what is the time scale.
Knowledge is the key to dealing with this, once you have that your brain can start to make some sense of it.
Its not vain to worry about losing a breast, I hated the thought initially that it may happen but my husband said if it's trying to kill you then it's going! As it happens I had a lumpectomy and still have a normal ish looking boob, of course if I needed to I would have had a mastectomy but like you my initial thòughts were that I didn't want to.
Write down all these thoughts as they happen and put them in to some sort of a questionare to take to your appointment, as you have found they are lovely and will happily answer you and help reassure you at every stage, just be prepared for more waiting over the next few weeks , it seems like for ever at the time but things do move pretty quickly, I had my appointment on a Monday and my op the following Friday.
Plenty of ladies here to chat to so feel free to pick our brains anytime Xx Jo