N/C as my name is pretty easily searched for by friends/family.
So I've seen a lot of talk about "bra intervention" threads over MN threads and finally found a link to the Bra Guru Fitting Guide so now I know what you're talking about.
Here's my problem...
I'm a 36" ribcage (which I already knew. I've tried 38 but they ride up at the back even on the tightest hook) and measuring a 57" in the boob part (21" difference). So my question is this. The website only says:
A,B,C,D,DD,E,F,FF,G,GG,H,HH,J,JJ,K,KK,L…..there is also the AA, which is smaller than an A. For each inch difference between your band size and your overbust measurement, you get a cup (starting at A) - so somebody measuring 30” underneath and 40” over would start at a 30GG.
Based on that I'm supposed to count up 21 cup sizes starting with A but L is 17" so.... now what? Does it go LL, M, MM, N? So I'm an N? Is that how this works? 
My next question is... what bra brand goes to that size? I've been unable to find an L/LL (which is what I was guessing I am prior to this, I know I'm bigger than a KK as that's what i'm wearing right now and I have the dreaded "4 boob"... but I order my bras online so can't try them on until I get them) so how the bleep do I find an 36N? 
HELP! I'm already looking into taking a course to make my own... is this (or a professional making them) my only option?
TIA!