got measured in john lewis yesterday she said i was 32DD the bra i tried on seems to fit ok, a bit of side fat i bought a similar bra today... it doesn't fit. I have bottom heavy boobs so the top is two great big gaping holes.
Scooping is your friend when the band feels too tight.
Have a search for past bra intervention threads from about June I think.
I am also quite poor but have found M&s are crap, cheapo places like primark are all too narrow on the band so it cuts in, moulded bras are just wrong wrong wrong for me, supermarket ranges seem to have very wide cups.
I bought 2 bravissimo online in their sale and am converted to the 'up and at em' forward pointy shape. Made me look like my top half had lost a dress size, and made me look a younger shape in my clothes.
So I got 2 bravissimo in the sale, and 6 weeks later got a freya a bit reduced in debenhams. Yes even in the sale they are more expensive than any bra I would have considered before, but soooo worth it.