Over the past year one of my pretty symmetrical breasts have changed in size. 

I was a size B, for some reason when they stopped fitting I didnt think about it when dropping down to an A. 

Its only recently when I was mentioning pain in my breasts more consistently (which I put down to hormones) that I noticed the pain was always in the same spot on my left breast. 

Its also my left breast that is shrinking, as my right breast can still fit into B cup bra's. 
My partner noticed the size difference before I did. 

My GP has had a feel and said she can not feel anything, and they dont seem too different in size. 
She did not seem to acknowledge the pain or my protests of being the same size a year ago.  I explained I only just swapped down to As in March. My breast now does not fit in my new bras bought to fit only months ago.
She referred me to a breast clinic (for my own peace of mind) but said there was no urgency because she cant feel anything and I have to wait and see if they will accept me. 

There was no mention of further investigation on her part, and she did not acknowledge the pain at all. 
So now I feel even worse then before I went, I'm also worried I wont be accepted for an appointment because she did not seem all too bothered so fear she will not send over an accurate report.

The change is noticeable and the size difference is obvious to my partner and family members i've shown.

What should I do?