I've been wearing 34C for ages now not sure how I even started wearing that size, it just seemed to fit 
I'm a size 10 and my boobs are small, just about a handful, and I've done the bra intervention and my back measured 31" with the tape nice and tight, and my leaning forward fullest bust part measured 36" with the tape just comfortable around. Going by the blog I should be trying a 30 or 32 band with an E cup?! Seriously?!