I'm 'young' in the cancer world. At 45, I don't feel it, but in the waiting room of the breast cancer clinic I could see why the doctors kept referring to me as young. I cant even imagine how much worse that feeling is for you at your age. It brings up so many different emotions for me, it can be quite overwhelming.
I agree that it's hard seeing your family upset too. I just didn't want to have to tell my mum, as I knew it would hit her so hard. She's a worrier on a good day. I now worry about her worrying!!!
Mine is hormone positive, but there is someone on my husband's side who had hormone negative at 28 (don't know the full details as his family don't discuss these things very openly). She went through lumpectomy and all the treatments and had 13 years cancer free. Only to then have a brand new hormone+ cancer appear. Definitely quite unusual for that to happen, but she does have a few lifestyle factors. She's now had a double mastectomy, more chemo and on hormone blockers. 1 year later and so far so good. There is no family history at all. I know it's not the same as your situation, but hopefully it's useful information for you.
After her first cancer, the lumpectomy, radiotherapy and chemo, she went on to have 2 more children without fertility assistance and breastfeed both of them too.