Thanks Big Dave.
The site is level and compacted- we ended up laying a patio on the site so it would be level and easy care.

The material in the compressed corners appear to be folding outward, like a small folded pocket, whereas the joints on the other two corners seem to be expanding and they look stressed. I wasn't sure if it would all expand properly once the water pushes the walls into alignment. I fear that the corners have gone wonky and two of the corners are too big and the other two are too small. They looked good when we started filling, so I had hoped that this was normal. We tried to manipulate the corners but the water weight is too great.

Darn- I wish I didn't need to empty the pool. Maybe I don't need to take all the water out.