I'm a 28 G, so know exactly where you're coming from. I've never tried Boux Ave (mainly because they do so few underwear sets with suspenders), but what I tend to do is if I find a bra I like try on a size where the cup fits around my bust properly and then have the back altered. This can be tricky at times, as if the back size is a 38 or if the back of the bra is very fancy it won't look right having it taken in quite a few inches. I find it usually works best on back sizes up to 36 (and this depends on the make of bra too as some back sizes differ from company to company). It is a mine field out there, but I find this is the easiest option for me.