I didn't really have any of the signs of an ill fitting bra either, I could pull the band out more but it wasn't riding up or away from my body at the front. The main thing was when I leaned forward the cups would gape a bit and not support me fully. This made me think I was wearing too large a cup size but I really didn't want to go into an A cup and I was too embarrassed to get measured. Thanks again to runningfromfat I measured myself properly and I'm a 32D and it makes a huge difference. My boobs look awesome now haha When I put my old 34B back on it was just terrible.
Not sure about brands and stuff but there's lots of cheaper bras on ebay. Look up Freya bras in your size and see if you can pick something up cheap.
I was disappointed when I realised Primark didn't go below a 34D
but ooooh well. I got a nice Marks & Spencers bra too, good bras are a bit more expensive but you can totally feel the difference.
Good luck anyway!