Please! 
I have just measured using the method described here and am 32" underneath (could probably pull it tighter but 32 is not loose) and 43" on top. I am usually about 28" underneath and about 38" on top. I have been guessing and wearing a 34H of late but my cup is overspilling in comedy extremes.
I just don't know what to try -- am 29 weeks pregnant, still wearing underwires comfortably but will inevitably move into nursing bras post-birth. I am still sort-of breastfeeding my two year old DD but she isn't taking much milk, if that makes any difference.
Happy to shop around and spend a bit if need be but will probably be mostly restricted to online.
Any expert advice very gratefully received!