Breast clinic tomorrow and terrified - indent and bulging vein/ligament

Trying not to completely lose it… when I lift my left arm I have a very obvious dent/flat bit on the inner bottom quadrant right next to the nipple and a vein or ligament  that is easy to see and feel. I think the ligament may always have been prominent though. Sometimes I can see and feel them on my right breast too.

I get offered screening through work snd had a mammogram and ultrasound late Feb/early March. Both fine although I do have v dense boobs.

I’ve lost loads of weight recently (down 3 cup
sizes) and have been working out but I’ve loads of loose skin. I’m 46 so usual hormonal changes too. I’m just praying there’s a plausible explanation  

Got my appointment at the breast clinic tomorrow and I’m so scared. I’ve been down a hole with Google AI and ChatGPT and am now convinced I’ve got something really aggressive like TNBC that didn’t show up on my scans 6 months ago but is causing the symptoms now. 

Guess I’m just here for a bit of a handhold really. The next 24 hours or so are going to be tough. Just don’t want to let anyone down.