I was recently in the nearest large town to us so I went into M&S (having found nothing 'just right' in our Debenhams).
6 years ago M&S measured me as a 38b. They measured me OVER the ill-fitting 36B I was wearing at the time, having changed shape after dcs.
These threads told me I should be a 34DD. So I filled a basket with a selection of 34 D and DD, and a couple of 36D. Headed for the lingerie changing room. Assistant tells me 'wait there the fitter is not available at the moment'.
I barged past her saying 'I don't want a fitter. Your fitters measure me and sell me bras that ride up at the sides if I so much as hiccup, with bands that are an inch away from my ribs at the front, wires that end up half way over my boobs, and in which my boobs are not supported, but just hang there covered in lace. I am just going to try all these on till I find the right size for me.
I tried em all on. And mumsnet was right. I have a few 34dds now and all fit perfectly. No riding up, boobs pointing more or less forwards instead of down and to the sides, band sitting flat all the way round. I keep looking down as they are sort of separate and stick out instead of being squashed to my chest!
So, was talking to my neighbour that same afternoon when we took the kids to the park. She said
'you can't be a DD, that's really bazooka-ish'
So I told her how to measure, how it should fit etc, and this look of 'clouds clearing' came behind her eyes and I bet she's in bloody marks this weekend.
In this warm weather all my summer dresses look fab with my new shape boobs!
I started wearing bras 30 years ago, and up till LAST WEEKEND I know know that every bloody one of them for all those years has been the wrong size and I am not flat chested!!!