And yep, I definitely had 20m the first time as I need to buy a fair bit more to make another few layers.
So I will need to decide on how to go about assembling the layers I do have. Two skirts each with 20cm ruffles and one gored shape and a lot of deeper flounces left over. In theory I should be able to put the two ruffled layers face to face and use the last gored shape to put the larger flounces on. I may just do that. The net is a bit thin is my only worry.