oompa has suggested I give this a go.
I'm 5'9" size 12 and have been wearing super padded bras in a 36A.
I really don't have much, indeed I look like a teenage boy in a speedo cossie.
According to the guide I should be a 34B.
Have now ordered a 34B thanksJLclick&ollect but I'm convinced those cups will be empty.