One sore breast

[JESS1211]

I'm 41 and over the past few months I've noticed a sore patch on my right breast. I couldn't feel any lumps. At the same time, I noticed that might right breast is bigger than the left, but it may have always been like that, I'm not sure. Because of the soreness I focused on it more. Anyway I saw my GP who wasn't concerned but sent me for an ultrasound of both to be sure. All was fine.
The soreness still bothers me, and the size but I've been given no explanation for it.
Could this be perimenopause? Other symptoms I've noticed lately are bigger breasts generally and short length periods.
Had anyone else had pain in just one breast and a slightly bigger breast? And was it due to peri?

I have the same except it's the left breast. I have private health benefit with my job, so I went in to a private hospital, got a mammogram and ultrasound. They found cysts but not cancerous. I was told it is hormonal. I was told to take evening primrose oil every day and to wear a bra 24/7 and avoid lifting heavy loads. I am 43.

Yes I have this. Aged 42.
Left only. I had a mammogram and ultrasound and nothing untoward but it does still really worry me as my mum had breast cancer.