Breast indent

Unsure what I am expecting to get from this but need to vent. 

In February I noticed an indent in my left breast. It comes across my breast from the side of my armpit along towards my nipple. My left breast also seems substantially larger than the other, which hasn't always been the case. 

I seen my GP in March who referred me urgently to breast clinic. I was told 40 week wait. I have been back to my GP this week due to severe lower back muscle spasms but they decided to also check the indent at the same time. 

The indent is larger, kind of puckered and feels like a gap underneath. They said the edges have hardened around it. The skin is tethered where the indent is. They have now referred me again as the two week suspected breast cancer referral. 

I have large lumpy breasts and they have explained physical examination is limited due to this (36HH). I have breast fed both of my children, having stopped breastfeeding over a year ago. I have noticed on my nipples that there is white discharge, but I would have to squeeze it out, if that makes sense. 

I feel like I'm spiralling with worry but also on the other hand convinced that surely it can't be anything serious (like it can't happen to me). 

There is no lump that i can feel, but again, this is difficult to check as i have very lumpy feeling boobs anyway. I feel so confused.