My wife ordered a size up from her usual, and it was way too tight, could not even close any of the zipper. She went large thinking she would have it tailored, but it was too tight to even try to let out. I would say the size 4 but that maybe to small in our experience.
There is no phone number listed for Hebeos. They only communicate via email. Do NOT order from here because they will NOT give you a refund, no matter what.