Dent in breast and feels like a hole?!

Hi, I'm hoping I can find someone with similar issues as mine as I'm driving myself crazy! A few months ago I noticed a tiny dent in my breast, right under my nipple on the areola. Last weekend I caught sight of it in the mirror and i think it has gotten slightly bigger so I went to gp who has referred me for urgent 2 week appointment. I know how all of this goes as my sister has metastatic breast cancer in her bones and I was there from when she was diagnosed, through chemotherapy etc. Part of me feels that surely a family can't be so unlucky to have two sisters diagnosed within 5 years but I don't suppose cancer really cares who it targets! My main curiosity is that when I push the dent I can almost feel a hole, as though there is missing tissue. I can't find anything about this online , good or bad so I just wondered if anyone else had experienced this.