Wow! Thanks for your advice. 
After trying several different sizes I've settled on 34f. I just got a couple from Next to keep me going until I completely stop breastfeeding, when I will go mad at Bravissimo- I've seen loads that I like on that website! 
The central gore sits perfectly- I finally have two distinct boobs after 4 years of nursing bra monoboob hell! I am having some discomfort around the front of my ribcage, but I suspect that's due to the fact that I'm not used to wearing underwires anymore, or having a bra that fits correctly...
I can't believe the difference in my silhouette- I look like I have pert boobs and somehow my waistline looks better too. Amazing, thanks again!