Find something with a v neck thats large enough to fit your boobs, has a waist tie so it'll fit your waist. Coats with flared skirt sections work well and use a scarf/pashmina to keep your neck area warm if its really chilly. I'll see if I can find a pic. I'm a 36H so I know the feeling, I've always managed well by going with this method - also if you can stretch - buy a really good quality coat. My current one was stupidly expensive (around £200 iirc) but its lasted me nearly 4 years now and still looks new with the only thing needing fixed is the buttons sewn back on from being slightly stretched through pregnancy wear.
Edit: something similar to this, wide v neck, tight belt....skirt section could be more flared if you can find it, but it doesnt seem to be the fashion just now.
https://www.buybuyseller.com/images/s/201111/a/Womens%20Long%20Coat%20y1201.jpg