Welcome! We know it's not where you want to be but you are with friends. My brush with bc started in a similar way, no
lump, just a very tender and uncomfortable breast. Mastectomy, 6 months chemo, 12 months herceptin and 5 years hormone therapy. I hit 5 years after diagnosis next month, and will end hormone therapy next May, all going well, fingers crossed!!
Many others (not me!) have been involved in medicine and cancer related treatment before being diagnosed themselves. I can imagine that you have much more information than I had (no cancer at all in my family, no personal experience of serious illness or injury) but everyone has different responses and these also change over time. This a good place to talk, let off steam and also share a joke or two, there's a rich stream of humour here! Very best wishes and keep your eyes on the future. One of my favourite quotes from one of the many terrific contributors here, is "Don't look back, you are not going that way".