Jut wanted to update this thread. I discovered that a website called
Martial Arts Mart Has a selection of womens Gi and they go up to a 1x which seems to be about equivalent to a size 6.
This is the Century Gi that was mentioned earlier in the thread. Tops and bottoms are sold separately.
I purchased the 10oz extended length in the 1x size. After the initial purchase confirmation I did not receive the promised notification that it shipped but it did arrive within a week. I have worn the jacket to a couple of classes now and have found it to fit well and is comfortable. The material was soft and supple right out of the package and washed swell. It has not so far shrunk much but I am hoping that with a few washes the sleeve and tail length will be reduced a little. My only issue is that the tie strings are much to low on the jacket and I will need to move them so they hold the jacket closed correctly. But this is a small thing. Overall, out of the box it has been fine to train in. Probably the nicest and best fitting Gi jacket I have owned.