Breast shrinking worries

So I just got a red flag referral to the breast clinic yesterday and am feeling a bit overwhelmed. I always thought breast cancer would cause a breast to appear larger, but since discovering a lump last week my breast seems to have shrunk with noticeably less breast tissue in it. The GP really didn't react at all - I think she was trying to keep me from worrying, and didn't address the issue of the breast shrinking, although did notice it was smaller (it isn't usually). I guess I'm just wondering if anyone else has had just one breast shrink and wondering if it means anything?

I'm also worried as she said that referrals are taking a while, so although I'm red flagged (2ww) I might not hear from the hospital until after Christmas and it could be 6 weeks before I'm seen! I'm trying so hard not to overthink it, but waking at 2am and not getting back to sleep until about 5 when I have to get up for work at 7 is draining and I don't know if I can maintain that for 6 weeks!

Words of advice or shared experiences would be most welcome :)