I've followed the instructions on the many threads here and I think I'm nearly there...
Measurements 33 and 41. I was previously in 34DD (fitted years ago in John Lewis, have put weight on since). I'm a size 10/12 for clothes, and also short 5ft3 with either a short upper body or high set boobs (or both!) as a lot of necklines are too low for me.
34DD occasionally gave me quad boob, had a bit of a side boob thing going on and also jiggle when walking fast. 
So, I think my new size is 32FF or 32G, yes?
I haven't had time to get to a shop with a good selection yet, but I did manage to get a Chantelle bra in 32FF from TKMaxx and it's already made a huge improvement. The only thing is, my boobs still feel/look quite far apart from each other? I don't know if that's just down to the style of bra, or my body shape, as I had that issue in the old/wrong size too. But it looks ok generally - sits flat in the middle bit, has no side boob, and feels very supportive.
Also hopefully in the process of losing weight so don't want to spend lots on new bras now in case my size changes but I do need a couple of pairs so that I can confidently wear tops/dresses without hiding my boobs under scarves or floaty layers...
As an aside, why oh why don't shops realise that you can be a 32 band size and need a larger than C cup?! So many DD+ ranges are all huge band sizes. No wonder so many women are in the wrong size if they never see the right size in shops.