Double mastectomy after testing positive

So I really want to do everything I can to prevent myself from getting cancer. My doctor didn’t tell me about this option. When I brought it up he made me feel like it was too extreme. Like I was being ridiculous.

I’m 21. I am positive for BRCA. I also have NF1 and possibly lynch syndrome.

What are your thoughts and advice

Also do you think 21 is too young? I honestly feel ready. I’m young and strong now. I don’t have kids to worry about and I’m not concerned about breast feeding.